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Industrial Chemical Monographs 

Fixation, of 


Industrial Chemical Monographs 



Fixed Nitrogen Research Laboratory^ U.S. Dept, Agric.; Formerly with 
the Nitrate Division^ Army Ordnance j American Cyanamid Company 



Eleven Henbietta Sthbet, W.C. 2 




li Y T H U 1‘ iH 1' T O N 1‘ R E S B • N 1.1 R W O O 0 ■ MASS, 


Although several books and a large number of pam- 
phlets Or articles have been written on various phases of 
the fixation of atmospheric nitrogen, these have been for 
the most part written by and for the scientist or technician 
intimately interested in or associated with the work. 
From the Jarge number of r^uestions and the nature of the 
questions asked at the various technical society meetings 
and from the number of letters which have come to me in 
my official capacity on the staff of the Fixed Nitrogen Re- 
search Laboratory, it was very evident that these books and 
pamphlets had not served all requirements. It was then in 
an endeavor to fill a need as was indicated by inquiries both 
personal and by letter that this small volume was written. 
This book is not, therefore, intended for the scientist or 
technician familiar with the subject of the fixation of atmos- 
pheric nitrogen, but is intended for the technical man of 
other walks of life, for the teacher and student, for the busi- 
ness man and the hanker. It is hoped that this small con- 
tributiciii will give the general information necessary to 
iiiffuencc Its reader to become more deeply interested in the 
subject and seek the other and more technical writings on the 
subj ect. 

In this volume an attempt was made to show the necessity 
for nitrogen, and its sources; to give sewne historical facts 
leading up to the present industry, to give a general descrip- 
tion, neither wholly chemical nor wholly engineering, of the 

Chapter I 


Nitrogen, the supply of which in utilizable forms is now 
engaging the attention of all of the important and progres- 
sive countries of the world, is one of the most plentiful 
of the elements. 

Although the ultimate source of practically all nitrogen is 
probably the atmosphere, there are today four generally ac- 
cepted commercial sources, viz., the organics, the deposits of 
natural nitrates, the deposits of coal and peat, and the 

For thousands of years the use of nitrogen compounds 
was confined to the fertilizing of the land by the return to it 
of animal and vegetable refuse. Just when such practice 
was actually started by man is not known. It is reported, 
however, that as early as the fourth century B.c. the Egyp- 
tians utilized camel dung which they dug from the Libyan 
Desert near the temple of their god ‘‘Ammon.” It is 
supposed that a salt comparable with our present “sal am- 
moniac ” was also produced from this material. In ad- 
dition to such manures, the organic nitrogen materials of 
today include dried blood and tankage from the slaughter 
house, cottonseed meal from the oil mills, fish scrap, leather 
scrap, waste products of the cocoa factory, and other simi- 
lar materials. 

The use of Inorganic uitrogeu started with the discovery 
of the natural saltpeter deposits of India and for years a 



FIXaVTION of atmospheric nffrogen 

lively trade in this material with the other countries of the 
world was enjoyed. With the discovery of black powder, 
the manufacture of which depended upon potassium nitrate, 
these Indian deposits immediately assumed a position of 
even greater importance. I'he nations of the world were 
now dependent upon India for the material necessary for 
national defense and preservation. 

The demand fur nitrogen compounds rapidly increased 
with this introduction of military explosives and finally led 
in 1830 to the discovery of the vast deposits of sodium 
nitrate in Chile. Although these Chilean deposits almost 
immediately assumed a position of importance it was with 
the discovery of a meiaod of manufacturing nitric acid, the 
basis of our present smokeless powder and high explosives, 
friim this sodium nitrate that their real v'alne was recog- 
nized. Chile for years was almost the sole source of supply 
of the world’s inorganic nitrogen demands for both peace 
11 nd war. 

Toward the end of the nineteenth century, another source 
of available inorganic nitrogen was introduced with the 
bringing into operation of by-product coke ovens. Coking 
coals ccintain combined nitrogen in varying ([uantities‘ up to 
about 40 pounds per ton. In producing enke in the beehive 
type of oven all this nitrogen, as well as many other valuable 
constituents of the coal, are lost. In the by-product ovens, 
however, a part of this nitrogen is driven off during the 
coking process and 4 to 5 pounds per ton of coal coked are 
recovered as ammonia. 

Although it was long known that the atmosphere every- 
where about us was composed of nearly So per cent nitro- 
gen, this vast and inexhaustible source of supply was nnt 
ntilizeil until the beginning of this twentieth century. With- 



out this source of supply the World War would never have 
contiiiued for four years. Genuaiiy, because of an insuffi- 
cient supply of explosives, would undoubtedly have been 
forced to abandon hostilities at an early period. Yet even 
though her fleet was held inactive she taught the world a 
valuable lesson. At the very outset of the war, Germanv 
with but a few converted freight and passage ships, pre- 
vented the exportation of nitrate from Chile for several 
months. This blockade was so complete as to cause a very 
alarming situation before it was broken. It demonstrated 
the possible helplessness of a nation relying for its national 
defense, in fact for its preservation, on a foreign source of 
supply for Its inorganic nitrogen. In time of war greatly 
increased quantities of nitrogen are necessary not only for 
explosives but for agriculture as well. The armies In the 
field must be well fed while the health and hence contentment 
of the people at home is also of paramount impcirtaiice. 
Just as an army cannot be expected to fight effectively on an 
empty stomadi, so a hungry nation cannot be expected to 
support its armies. If the nitrogen supply is sufficient sci 
that the armies are victorious, but insufficient to provide also 
for the needs of the remaining populace, then the cause 
will undoubtedly meet defeat from within. 

It is very evident that the consumption of war-time agri- 
cultural nitrogen should be at least equivalent to, and if at 
all possible, greater than the peace-time consumption. 
Nitrogen for explosives must be additional. If the nitro- 
gen is imported from a foreign source of supply, the neces- 
sity for increased transporting capacity for this war demand 
occurs at the time when the country can least afford to divert 
additional bottoms to this pu impose. If a blockade of this 
foreign source of supply — such as was successfully main- 



tained by Germany for a period at the beginning of tlie 
World War and was maintained against Germany during 
the whole war — is effected, and the country is dependent 
upon this source, then that country is almost inevitably 
doomed to defeat through lack of munitions or starvation, 
or both. 

By increasing the consumption of agricultural nitrogen, 
larger yields per acre may be expected. This will result 
in either a greater total production or an equivalent produc- 
tion from smaller acreage, and hence with less labor. Such 
Increased use of nitrogen might be a remedy for some peace- 
time as well as war-time agricultural difficulties. 

It is quite generally believed that Germany declared war 
ill 1914 only after assuring herself that she had a suitable 
source of fixed nitrogen within her own borders. The rate 
of consumption of nitrogen in explosives during this war 
was undoubtedly far beyond the expectations of any indi- 
vidual Or nation. In order to meet this demand it was nec- 
essary, even with the enormous expansion of the rather 
young atmospheric nitrogen fixation industry, to stint agri- 
culture. How great an effect this had on the eventual re- 
sult is rather difficult to appraise, but there is no doubt that 
the people of several of the warring nations suffered materi- 
ally and still show the effects of malnutrition. 

Although agriculture in peace time and agriculture and 
military explosives in times of war are the large consumers 
of nitrogen, it is being used in rapidly increasing quantities 
in many Industries. Agriculture is responsible for approx- 
imately 80 per cent of the world’s inorganic consumption. 
In the United States, as much as 40 per cent of the con- 
sumption is in chemical industries, the remainder going to 



Explosives arc no longer to he associated only witli 
war- The use of peace-time explosives has grown tremen- 
dously until today there is consumed in such pursuits as 
mining, quarrying, road building and the cleaning of laud 
for cultivation, about 500,000,000 pounds annually of 
high explosives. The chemical uses of nitrogen, largely in 
the form of nitric acid, arc in the manufacture of photo- 
graphic films, artificial leather, artificial silk, imitation ivory 
and dyes. In the form of ammonia, nitrogen is used in the 
refrigeration industry for the manufacture uf artificial ice 
and in the operation of cnld-sturage plants; it has a wide 
domestic use as household ammonia, and is used in the manu- 
facture of soda ash, one of our most important staple 

The provision of an adequate supply of such a vital 
material must receive the greatest consideration of the vari- 
ous nations of the world, both individually and collectively. 
Four sources of supply were mentioned earlier and as it 
has been shown that an unlimited supply is vitally neces- 
sary, it will he well to consider the extent of these 

Since soil nitrogen, or what maybe considered the natural 
nitrogen of the soil, is almost wholly confined to the surface 
portion and since the uiiweathered, underlying rock is devoid 
of nitrogen, it is evidently of atmospheric origin. The 
accumulations of soil nitrogen are the results of residues of 
many generations of plants. This natural combined nitro- 
gen is largely a constituent of organic matter and as such is 
unavailable for plant use. It must he converted into simple 
water-soluble compounds. The decomposition of such or- 
ganic materials results in the conversion of the combined 
nitrogen to ammonia. This ammonia is then oxidized by 


the soil bacteria to nitrites, which are further oxidized to 
nitrates, which are quickly taken up by the growing plant* 
Such accumulations of tlie sail nitrogen cannot be considered 
as a source of our future supply of nitrogen. 

The fixation of nitrogen is also accomplished by the bac- 
teria within the tubercles of the plants. Professor Haber 
once remarked that the fixation of nitrogen in the future for 
soil fertilization use would not be through great imlustrial 
plants, but rather through plant and soil bacteria. Sod cini- 
ditioiis readily influence nitrogen fixation by legumiiians 
vegetation, particularly the supply of lime, and orgaiiir mat- 
ter uud the aei'iLtion of th^ soil. Tests have shown tly..t tou 
to 200 pounds of nitrogen can he gathered in a gnod crap of 
leguminous plants per acre. At the present time, Imwcver, 
this method of nitrogen fixation cannot he de{)ciided npnn to 
supply our nitrogen demands- 

While the natural manures arc widely used as fertilizer, 
yet their availability is practically limited tn this use. Siuh 
manures are a by-product and the supply cannot be in- 
creased at will. The same is true of fish scrap, dried hliiiiih 
tankage, cottonseed meal, cocoa waste, etc. Appmximately 
70 per cent of the combined tonnage of these materials is 
used for cattle feed, while the remainder is eonsniueil in 
mixed fertilizers. Such materials cannot then he cansidereil 
as a primary source of Supply of nitrogen, but must he sup- 
plemental to some other source. 

In 1898, the world was rather rudely awakened by a 
statement by Sir William Crookes, an eminent authority, to 
the effect that the world was facing ultimate starvatinii be- 
cause of its dependence upon the natural niter beds of Chile 
for its nitrogen supply. While later investigations have 
given assurance that the exhaustion of these deposits would 



probably have been further distant than was feared froni 
Sir William’s statennent, yet his warning was well founded 
and timely. 

At this time it appears certain that Chile could snjiply the 
total demands of the world fur at least luo years cnta thr 
future. It is Inevitable that exhaustion must aecur, hnwever, 
and wisdom was shown in anticipating this cniiditicin and 
guarding against its consequences* Although the 2240 
square miles af nitrate-bearing ground which has been ex- 
amined and proven is but 3 per cent of the total nitrate area, 
yet there is no assurance that the remaining 97 per cent is nf 
proportionately equal value. It nnght be assnrncd that the 
more likely areas have been worked first. On the ntlier 
hand, future working af this area might show these unex- 
plored regions to be vastly more valuable than the present 

There is still an economic c|uestion tci be considered, 'The 
world, in consuming snme 2,ooo,aoo tons of Chile nitrate, 
has contributed to that country’s support through the cxporl: 
tax nearly $25,000,000 for the year 1926. Of this ainuunt, 
the consumer in the United States paitl apprnximatidy 
$12,000,000. If nitrogen equivalent ta that supplied by 
this material could be secured within the borders uf the 
United States, even though at the same cost to the cmi- 
SLimev as Chile nitrate, the country as a whidc woidd benefit 
to the extent of $12,000,000, the tax which wnuhl have 
been paid to Chile. If, on the other hand, pradnetinn costs 
are such as to permit reduction in cost to the cansumer, the 
dual benefit can be immediately seen. 

This source of supply in Chile, while of great extent and 
sufficient for a long period of continued exploitation, is also 
of limited value both because of eventual exhaustion and 



also because of the possibility of a nation being sliut off 
from this supply when it is most needed. 

The third source of supply, coal by-products, is also lim- 
ited. Wliile coal, unlike sodium nitrate, is common in large 
deposits to many parts of tlie world, its by-products cainiut 
be relied upon to furnish a nation’s inorganic nitrogen. The 
nitrogen from tins source must be a by-product and hence 
its production will not be dependent upon the demand for 
nitrogen but rather upon the demand for coke. An increased 
demand for nitrogen might be met by a decreased supply 
from this source because of conditions which might have af- 
fected the coke market which in turn depends upon the iron 
and steel industries. 

These three sources of supply then must be considered as 
wholly inadecjuate. No nation can today afford to place en- 
tire dependence upon any one, or even all of these three 
combined. These sources must be considered as supple- 
mental to some other principal source. This principal 
source is the atmosphere. 

The fourth source of supply, the atmosphere, must then 
be the answer to the important question of an unlimited 
supply. No nation is more advantageously situated as 
regards this source than any other. It forms, as was pre- 
viously stated, nearly 8o per cent of the air wc breathe. 
Over every square mde of the ea,rth there is some ^0,^)00,^)00 
tons. Ill fact, the atmosphere furnishes an inexhaustible 
supply. It is apparent then that difficulties which prevented 
its use were present and were only recently overcome. 

Nitrogen is one of the more remarkable of all of the 
ninety elements so far discovered. In the free form as it oc- 
curs in the atmosphere it can be utilized neither by the bodily 
mechanism nor in explosives or fertilizers. In the free state 

NITROGEN , . '9 

It is a comparatively inert gas, but once it enters. into com- 
bination it d.LS[ilays the greatest activity both in the organic 
and inorganic fields. Owing to the slight affinity between 
nitrogen and the cither elements with which it enters into 
combination, many of its compounds arc unstable anil can 
be decomposed with the almost instantaneous evulntion af 
heat and gas. Because of this slight affinity, military ex- 
plosives almost without exception are nitrogen compoinids. 

Ill order to render this free nitrogen available for use 
other than as a diluent for the oxygen of the air, it must he 
combined with other elements. In this fcirin it is known as 
fixed nitrogen. The nitrogen cif the organics, nf ChUe ni- 
trate, and of by-product coke oven ainiiicinia is already 
fixed. In these cases the fixation has been aceoinplishcd by 
slow natural prcicesses. In the rapid fixation processes iiDw 
employed, the natural independence df the element has been 
overcome by the ingenuity of ‘man. If oxidized anil absorbed 
in water, it is fixed as nitric acid. This is the Arc Process for 
atmospheric nitrogen fixation. Calcium carbide at red heat 
will absorb free nitrogen as a sponge will water, thus 
fixing the nitrogen in the fcirm of calcium cyan amide by the 
Cyanamiiic Process. Nitrogen will ccimhine directly with 
hydrogen under certain cnnditiciiis, resulting in the fixing nf 
tlie nitrogen in the farm of ammonia, according to the Di- 
rect Synthetic Ammonia Process. 

Nitrogen fixed in these forms can be readily converted 
to other materials. Practically all modern explosives are 
made by treating various substances with nitric acid; for in- 
stance, smokeless powder from cotton and nitric acid; nitro- 
glycerin, the basis af dynamite, from glycerin and nitric acid; 
picric acid from carbolic acid and nitric acid; trinitrotaluene 
— T.N.T. — from toluol and nitric acid; fulminate of mer- 



cury from mercury and nitric acid; and ammonium nitrate 
from ammonia and nitric acid. Calcium cyaiiamide gives 
up its nitrogen in the form of ammonia when treated with 
steam in an autoclave. Ammonia may be oxidized and ab- 
sorbed in water to form nitric acid. It may also be used to 
neutralize sulphuric acid to form ammonium sulphate; or 
phosphoric acid to form ammonium phosphate, or carbonic 
acid to form urea, or nitric acid to form ammonium nitrate. 

C 11 A p r \L \1 II 


Tuk chemist luis known for many years Iiow to convert the 
inert free nitrogen i)f tlie atmosphere inti) conipouiicls af 
nitrogen in his laboratory. As early as 1774 Priestly iso- 
lated ammonia, which in 1777 was shown Iiy Schcelc to 
contain nitrogen. Further work by Berthelot showed it to 
be composed of one volume of iiitriigeii to three vohinies of 
hydrogen. In 1781, Cavendish noted the formation of ni- 
tric acid when hydrogen was burned in air anil in 1800 
Sir Humphrey Davy made nitric oxide by passing air Over a 
wire heated by an electric current. In Deville passed 

a nitrogen-hydrogen mixture through a porcelain I’ube and 
found that ammonia was produced when the tube was 
heated to about 1300^0. Ahhough these and odier reac- 
tions of nitrogen were known, the relnctauce of this cleiiiciit 
to enter into combination limited progress far years tn the 
experimental laboratory. Tbc (|naiitities of product ob- 
tained in this early work were distressingly small. 

The warning of Sir William Crookes in 1H98, however, 
gave impetus to the work looking toward commercial fix- 
ation of the nitrogen nf the atmosphere. In 1902, the ap- 
plication on an industrial scale of the combined results of 
experiment and theory was attempted. In thjit year, the 
Atmospheric Products Company was cirgani7xil with a cap- 
ital of $1,000,000. This company took over dx process 
and equipment patents of two Americans, C. S. Bradley anil 



1 2 

R. Lovejoy, and erected a large works at Niagara Falls, 
New York, The hidustrial fixation of atniospheric nitro- 
gen thus had its birtfi in tlic United States, 

The process of Bradley anil Ltivejny efiects the direct 
combination of the nitrogen and oxygen of the air tn form 
nitric oxide. By furtlier oxidation and alisarfitiiin iif the 
oxides by water, nitric acid of approximately 35 per cent 
ccinceiitration is formed. This methnii of fixatiiin is known 
as the arc process. 

Altliougli tliis first plant iiiight well be callecf a technical 
success, it was not an ceciinmiical success and closed diiwm 
in 1904, after less than two years of nperation. The yield 
of 94B poLiiuIs of nitric arid per kiliiwatt year nf power em- 
phiycd proved iiisidHcieiit and tlie cc[iiipmenl besides being 
ciistly was rather fragile, requiring frec{ueiit repairs. 

The commercial possibilities fnr the direct tixidution of 
the nitrogen nf the atmosphere fnr the prodnetion nl nitric 
acid had been demonstrated. I lerc was a possible means 
of avoiding the serious situation indicated by Sir William 
Criinkes. liven before the plant at Niagara h’alls had 
discontiiined operations, a furnace was develnped in Nor- 
way by Friif. Cliristiaii Birkelainl and Faigiiieer Samuel 
Fyde, which proved to be both a mechanical and econoini- 
cai success, Fa^pe rime* its with this furnace using 3 iiorse- 
power were carried on early in 1903, and in October nf 
that year a small commcercial plant employing 150 horse- 
power was started in operation at Ankerliikken, near Oslo. 
'This plant proved so successful that the following year 
a plant of 1,000 horsepower capacity was erected near 

Tn 1905, the present works at Notodden were started 
into operation with a capacity of 2,500 horsepower. Sub- 


sequent enlargements brouglit the capacity of this phiiit hi 
40,000 horsepower in 1907, 55,000 in 1911, and 6h,oini 
in 1919. In 1911, the operating ciimpaiiy, the Nnrwegian 
Hydro-Electric Nitrogen Company (Norsk Hydro) started 
a second works at Rjukan, for a consumption of 130,000 
horsepower and added a second unit of similar size in 
1915. The Notodden and Rjukan plants arc still in upeni- 
tion with a combined consuniptioii uf 320,000 InirsepowcT, 
and an output of 38,000 tuns of nitrogen fixed per year. 

Odier arc process furnaces developed anil put into ciiiii- 
mercial operation are those of Schdiiherr, Moscicki, Paul- 
ing, Guye, and Wielgolaski. The installatians other than 
those at Notodden and Rjukan have been relatively siriall, 
so that the total installed capacity is approximately 45,000 
tons of nitrogen per year. 

Two further attempts have been made to establish the 
arc process in the United States. In 1913, the Southern 
Electro-Chemical Company, a subsidiary af the Southern 
Power Company, incorporated under the laws of the State 
of New York, erected a plant at Nltrolce, South Cariiliini, 
This plant employed the Pauling furnace and was equipped 
for nitric acid ennceiitratiim and ammonium nitrate pro- 
duction. The plant as enlarged in 1915 was of a eapneily 
to utilize some 7,000 electrical horsepower, fts total enn- 
sumption for tVic month uf March 1915, the heyt periiul nf 
operation, was at the rate uf less than half that amount, 

During this month, the ccjuivalent of 42,5 tons nf lofi 
per cent nitric acid was produced, while 32 tuns was concc'n- 
trated, 20,5 tons packed and sold and 10 tans cuiisumcil in 
ammonium nitrate manufacture. The manufacturing cost, 
$90 per ton of concentrated acid exclusive uf capital 


charges, and reckoning power at $io per horsepower year 
was high. This power rate of $ i o per horsepower year was 
far below the prevailing rate for that locality. The con- 
sumption of over three horsepower years per ton of nitric 
acid was too high, and rendered operation uneconomical, so 
that the plant was closed down early in 1916, and operation 
has never been resumed. 

In the following year, the third attempt at establishing 
the arc process in this country was made, and the fnst per- 
manent plant for the fixation of atmospheric nitrogen in the 
United States was started. This plant, erected and op- 
erated by the American Nitrogen Products Company, was 
of about one ton of nitrogen per day capacity and was lo- 
cated atLc Grande, Washington. After eiijoyhig nearly ten 
years of operation, the plant was destroyed by fire in the 
spring of 1927, and it is believed it will not be rebuilt. 

The search for mcaas of fixing nitrogen in the form of 
alkali cyinides for gold extraction led to the work of Frank 
and Caro, two eminent German chemists, during the close 
of the nineteenth century. The patents granted these inves- 
tigators in 1895—98 formed the basis of a process for the 
fixation of atmospheric nitrogen known as the cyanamide 
process, in which calcium carbide is produced through the 
reaction between lime and coke in an electric furnace. By 
the interaction of calcium carbide and pure nitrogen at a 
red heat, the nitrogen is fixed in the form of calcium cyan- 

The first commercial plant utilizing this process was put 
into operation at Westeregeln near Magdeburg, Germany, 
in 1905, This plant was not a commercial success and was 
abandoned in 1908. Some 800 tons of cyanamide had 
been produced the first year. A second and successful plant 



was started into operation in 1905, at Piano d’Orta, Italy. 
The initial capacity of this Italian plant was 4,000 tons of 
cyaiianiide per year. From this small beginning, the indus- 
try enjoyed a rather rapid growth to Its peak in 1918 of 35 
plants of a rated capacity of 350,000 tons of nitrogen per 
year. A large part of this capacity was erected for the war 
emergency, so that after the war there followed a curtail- 
ment of production and even a dismantling of some plants. 

The first cyanamidc plant erected on this continent and in 
fact the first successful plant for the fixation of atmos- 
pheric nitrogen was that of the American Cyanamid Com- 
pany at Niagara Falls, Canada. Tins company was incor- 
porated in 1907 under the laws of the State of Maine and 
in 1909 started into operation a plant for the annual pro- 
duction nf 5,000 tons of cyanamide. Subsequent enlarge- 
ments and improvements have increased the capacity to 

120.000 tons of cyanamide per year, equivalent to 25,000 
tons of nitrogen. 

When in 1917, due to the urgency caused by war, it be- 
came apparent that a large and positive source of fixed 
nitrogen must be provided in the United States, it was 
decided after careful consideration to erect a plant of the 
cyanamide priicess. This plant of a rated capacity nf 

40.000 tons of nitrogen per year, the largest cyanamide 
plant in the world, was erected at Muscle Shoals, Alabama. 
It is known as U. S. Nitrate Plant No. 2, and except for a 
two months’ test run it has never operated. 

Although attempts to produce ammonia directly from ni- 
trogen and hydrogen date back to 1807, commercial in- 
terest was not aroused until after the publication by Prof. 
Fritx Haber of a series of papers on this subject in 1905 
and 1906. The Badische Anilin Und Soda Fabrik, in 1910, 


took an active interest in the possibilities of this method 
for the commercial fixation of atmospheric nitrogen and in 
1913 started in successful operation a plant of a capacity of 
7,000 tons of nitrogen per year. From this start, world 
cajiacity of direct synthetic ammonia process plants has 
rapidly increased to an operating and under-coustruction 
capacity today of 979,000 tons of nitrogen per year. This 
is more than double the installed capacity of the cyanamide 
and arc processes combined. 

The World War proved a great stimulus to the atmOvS- 
pheric nitrogen industry. At the close of the year 19131 
or just prior to the outbreak of the war, there were in oper- 
ation seven arc plants of a capacity of 20,000 tons of nitro- 
gen per year, 15 cyanamide plants of a capacity of fi6,ooo 
tons of nitrogen and one direct synthetic ammonia plant of 
a capacity of 7,000 tons of nitrogen per year. Five years 
later, the close of the year 1918, there were operating or 
building and later put into operation, 12 arc plants of a 
capacity of 40,000 tons of nitrogen, 35 cyanamide plants of 
a capacity of 350,000 tons, and three direct synthetic am- 
monia plants of 330,000 tons. 

The period following the war has apparently favored 
the direct synthetic ammonia process. The capacities in 
tons of nitrogen installed and building for the various proc- 
esses at this time are: arc, 5 plants of 44,750 tons; cyan- 
amide, 28 plants of 315)500 tons; direct synthetic ammonia, 
51 plants of 979,000 tons. 

The first plant of this process erected in the United 
States was the U. S. Nitrate Plant No. i at Sheffield, Ala- 
bama. The imminence of war led to the passage in Con- 
gress of Section 124 of the National Defense Act of June 3, 
1916. This section made $20,000,000 available to the 


President for au investigation of the various methods for 
the production of ” nitrate and other products for muni- 
tions of war and useful in the manufacture of fertilizers.” 

There followed the appointment of a committee of scien- 
tists and engineers of the National Academy of Sciences in 
co-operation with the American Chemical Society at tlie 
request of the Secretary of War. In addition, two investi- 
gators were sent abroad to study and report on conditions' 
ill Europe. In the meantime the General Chemical Com- 
pany had worked up aod patented a modification of the 
direct synthetic ammonia process as operated in Cjermany, 
and made preparations for the erection of a plant. This 
plant of 7,5 tons of ammonia per day capacity was to be 
erected at Shadyside, New York. 

The result of the various investigations made for thn 
Government was the recommendation that the War De- 
partment take over the process of the General Chemical 
Company and erect a pilot plant to test the process. Ac- 
cordingly, U. S. Nitrate Plant No. i was erected at Shef- 
field, Ala. This plant of a capacity of 30 tons of ammonia, 
including the 7.5 ton unit which was to luive been erected 
at Shadyside, was never completed. Only one unit of 7.5 
tons of ammonia per day capacity was ready for trial op- 
eration prior to the signing of the armistice. Continuous 
operation of this unit was never realized, and ciiily a small 
amount of ammonia was produced. 

In addition to these three processes, a great amount of 
investigational work was done on other processes, and a 
large number of methods have been proposed from time to 
time for the commercial fixation of nitrogen. Very few of 
these have appeared to present promising possibilities. It 
must be remembered, however, that unforeseen develop- 


merits iu our knowledge, or changes in the industrial situ- 
ation due to new demands or supplies, may in the future 
make possible the commercial success of processes at pres- 
ent entirely impracticable. 

In die cyanide process a mixture of sodium carbonate and 
coke widi iron in small quantities is heated in a stream of 
pure nitrogen to a temperature of approximately 1000° C. 
This operation results in the formation of sodium cyanide, 
which may be decomposed with steam to yield ammonia. 

The commercial development of this sodium cyanide proc- 
ess was undertaken in the United States by the Nitrogen 
Products Company according to the patents of Prof. J. E. 
Bucher. Etxperimental plants were erected at Saltville, Vir- 
ginia and Greene, Rhode Island, while in 1918 the Govern- 
ment undertook the erection of United States Chemical 
Plant No. 4 at Saltville, Virginia, for the production of 10 
tons of sodium cyanide per day by this process. Operation 
of this plant started in September of that year, resulting in a • 
production of some four tons of sodium cyanide. As oper- 
ating costs proved to be too high to render the plant com- 
mercially practicable for the production of either cyanide 
or ammonia, operation was discontinued in December, and 
the plant was later disposed of through salvage. 

Of the various nitride processes, perhaps the one best 
developed is that for making alumiTixtmL nitride from crude 
aluminum oxide (bauxite) , coke and nitrogen, heated in an 
electric furnace to a temperature of about i8oo^’ C. The 
aluminum nitride may he decomposed with steam or di- 
lute caustic solution to yield ammonia and regenerate the 

Various small scale experimental plants of this process 
have been constructed and operated in France, Germany 



and the United States, The chief difficulty in all cases is in 
securing economically the I'igh temperatures necessary for 
the reaction, and in obtaining materials of construction 
capable of resisting these temperatures iu coutiiiuons opera- 

The explosion, or tlausser, process depends for the fix- 
ation of nitrogen upon die fact that by exploding a mixture 
cif combustible gas with air cir oxygen under proper candi- 
tions high enuugh temperatures can be reached to hriiig 
about die combination af a small amount cif the nitrogen 
and oxygen present. By this means it is attempted to bring 
about the same direct combination of nitrogen and oxygen 
that occurs in the arc process without its enormous expend- 
iture of electrical energy. 

Experimental plants in wl'ich operations have been con- 
ducted in stationary bombs witli media nically operated 
valves have been run at Heerlngeii and Neuremberg, Cier- 
many. The mechanical strains to which the a[iparatus is 
subjected limit the develo[)mcnts. In its [irescnt state of 
developmc-iit this pnicess cannot coiiipe e successfully with 
Other processes for the fixatioii of atmospherJe nitrogen. 

Of these processes, the arc process requires the greatest 
expenditure of electrical energy, the cyaiiamiilc ami nitride 
processes rank next, while the direct synthetic ammnnla, cya- 
nide and Jhiusscc pv,'~jCisases require only smal/ amonota or 
none at all. 

It Is interesting to note that commercial ilevclcipment of 
the three processes now in ciirnmercial operation stands 111 
approximately inverse proportion to the unit power con- 
sumption of each. For instance, only six per cent of the at- 
mospheric nitrogen fixed during 1926 was fixed’ by the arc 
process, which requires the expenditure of 61,000 kilowatt 



hours per ton. Tfie cyanamicle process requires au average 
of 14,000 (some plants as low as 12,000) kilowatt hours, 
or less than oiie-fourth that uf tlie arc process, auil was 
accountable for 24 per cent of the year’s production. Tlie 
remaining 70 per cent production was by means of tlie di- 
rect syiitlietic ammonia process, with ini average power 
coiisuniptiuii of 4,000 kilowatt hours per ion of iiitrogen 

The 6 per cent of nitrogen produced Iiy the arc process 
consumed 37 per cent of tlm total power used in fixing ni- 
trogen, the 24 per cent by the cyanamide prncess consumed 
35 per cent, while the 70 per cent by the direct synthetic am- 
monia process consumed only 28 per cent of the total power. 

The average power consumption at this time for the three 
fixation processes combined is 10,000 kilowatt hours per 
ton of nitrogen as compared with 70,000 kilowatt hnurs 
per ton 25 years ago. The total power ciinsuiiiption niiw, 
however, is at the rate nf 7,000,000,000 kilowatt hours 
per year, as compared with less than i,ouo,ouo then. 

Chap t kr III 


TiUi cummercial development of the arc process was the 
result of the attempts iif mtiii to emulate nature. It is esti- 
mated that through the lighlaiing discharge uf electrical 
storms 100,000,000 tuns of nitrogen arc fexed annually and 
carried to the earth’s surface by the precipitation of rain, 
snow and hail. Unfurtunately this fixed nitrogen is not re- 
turned to the earth at the time and place most convenient ta 
’man and he must resort to methads more under his control. 

In the commercial operation of this process, air is passed 
rapidly through a zone nf exceedingly high temperature pro- 
duced in an electric arc furnace. The heat of the gases cnii- 
taining the nitric oxide prndiicerl is recovered in waste-heat 
boilers, while the nitragen dioxide formed on cooling the ni- 
tric oxide in the presence i)f the accompanying Oxygen is ab- 
sorbed ill water, prodneing dilute nitric acid. This is the 
direct product of the arc process. 

The fuiidamental chemical reaction invedved is expressed 
by the c([uation 

N2-h02^'i NO — 43,200 gram cah.iries. 

From this equation it can be calculated that tlic chemical 
energy absorbed in fixing one ton of nitrogen is the equiva- 
lent of but 1,630 kilowatt hours of electrical energy. This 
chemical energy equivalem, however, represents less than 3 
per cent of the total electrical energy requirements, 6i,ooo 




kilowatt hours per ton nitrogen fixed. Over 97 per cent of 
the total energy expended is wasted so far as uctual nitric 
oxide formation is concerned, and is necessary for preparing 
and maintaining conditions favorable to the formation of 
the oxide. 

Nitric oxide exists in equilibrium quantities with heated 
air. For instance, the equilibrium amount at 2300° C is 2 
per cent, while at 3300° C it is 6 per cent by volume. As 
there natnraHy is a heat gradient of decreasing intensity 
away from the center of tlie arc but a relatively small quan- 
tity of the air attains a temperature of as high as 3300” C. 
Yet even though it were assumed that all the air passed 
through die furnace attained this temperature, still the 
great excess of total applied energy for heating over the 
chemical energy received in return can be readily realized. 
Actually the gases leaving the arc furnace contain an aver- 
age of 1.2 percent nf nitric cixiile. Tt is therefore necessary 
to handle 175 tons of tills gas mixture per tim of nitrogen 
fixed as nitric acid. As there is a temperature gradient 
between the arc filament and the SLiiTOuiiiliiig gas, it Is obvi- 
ous that this gradient should he as steep as possible. In 
addition to the saving of electrical energy which would 
otherwise be used for heating the gas if the gradient were 
flatter, the cooler gas snrniLinding the arc assists materially 
in reducing the temperature of the nitric oxide containing 
gases as they leave the arc filament. 

A factor working against an efficient utilization of the 
energy input is the rapid decomposition of nitric oxide at 
high temperatures. Although means have been devised to 
effect rapid cooling of the gases, yet it is believed that con- 
siderable decomposition actually takes place. It is by 
means of the operation of cooling the gases that some of the 



seemingly wasted energy input is recovered. The gases 
leaving the furnace at approximately 1 100° C are passed 
ihrertly to waste heat boilers where the heat given up in a 
ifrop i)f temperature to 350° C and further drop to 200° C 

111 ecanomi 5 icrs is utdized for the generation of steam. This 
steam hesities being used for purposes of solutions and evap- 
iiratiniis m used for the operation of turbo-generators for the 
generatitiii or regeneration of electrical energy. Although 
decnnipiisitlon of the oxide takes place at these lower tem- 
peratures, the rate of sucli decomposition is extremely slow. 

J he iJxi elation of nitric oxide represented by the equation 

'2 INTO -j- O2 ^ NOs -h 27^800 gram calories 

prnceedsS very slowly, so that the velocity of the gas must 
be liiw while the oxidation chambers must be very large. 

1 he fjxide leaving the economizers at about 200° C is 
further cnoled in cooling towers to about 50° C before it 
ciitevs the series of towers of the absorption system, since 
the cciin[ilcteness of the absorption decreases rapidly with 
increasing temperature. In the first tower of the system, 
the iixygeii of the accompanying air reacts with the nitric 
cixiile ti) form nitrogen dioxide. The gases pass in series 
tbrnugli the following towers of the al)iJOi"ption system 
where they are brought into intimate contact with water 
by which the iiitnigeii dioxide is absorbed forming nitric 
acid, reaction occurs according to the equation i 

3 NO2 -h H .0 ^ 2 HNO3 -h NO 

vvhicli la vsdiown in one step although actually taking place 
ill tw'ii. 

It will he; noted that nitric oxide is again liberated by this 
ahscirpdon operation. In fact, one third of the oxidi?-ed 



nitric oxide reacting with water in the absorption system 
reverts to nitric oxide which must be reoxidized. The re- 
oxidation of this nitric oxide, like the original oxidation, is 
a slow process. Because of this the absorption towers must 
be very large in order to permit tinie for the liberated gas 
to be oxidized and reoxidized until it Is eventually practically 
completely absorbed. The resulting product is a nitric acid 
of 30 per cent strength. 

In commercial uperatioa, only about 80 per cent of the 
nitrogen oxides are obtained in the form of nitric acid, since 
it is not practicable to obtain better absorption. Some 17 
per cent of these oxides then are absorbed in subsequent al- 
kaline towers over which flows a solution of soda ash. The 
absorption of the nitrogen oxides by this alkaline solution 
results in the production of sodium nitrite or a mixture of 
sodium nitrite and sodium nitrate, depending upon such con- 
ditions of operation as temperature and degree of oxidation 
of the nitric oxide. The equations for these two reactions 
are, respectively: 

NO -b NO. T 2 NaOH = 2 NaN02 T H2O, and • 

Q NO2 -h a NaOH = NaN02 -h NaNOg H- I-LO. 

Even with these alkaline towers, complete absorption of 
the nitrogen oxides is Hot achieved and some 3 per cent 
escapes to the atmosphere, if sodium nitrite rather than 
nitric acid is desired, alkaline towers alone should be used 
for the absorption of tbe nitrogen oxides. 

Although five different arc furnaces were mentioned in a 
previous chapter as having been used in commercial opera- 
tion, only three of these have enjoyed large-scale operation. 
These are the Birkeland-Eyde, the Schonherr, and the Paul- 
ing furnaces. 



111 the Bii'kclaiid-Eydc furnace, advantage is taken of tlie 
jihciiumeiioii of the deflection of an arc by means of a mag- 
iictir lichl nt right angles to it in order to spread the arc 
thriiugli the gas. The Schonherr fu mace is built upon an 
altngetliev different principle, the abject here being to secure 
a steady ami very long slender arc. The Pauling furnace 
niiire nearly resembles the Birkelaiid-Eyde, hi that it oper- 
ates cm the principle of a spread arc. In this furnace, how- 
ever, tins spread of the arc is obtained by a blast of air di- 
rected against it. 

I he Birkeland-Eyde and the Schonherr furnaces both 
are in nperutiiiu at the Rjukan plant of the Norsk Plydro 
Can'paiiy. d his plant is really the only large installation 
111 the are praccss. Its rated capacity of approximately 
qiijOcjo tiiiis af nitrogen per year represents over 70 per 
cl- at cif the wiirld capacity. 

This plant is in two units, of equal siz.c. Plant I, com- 
plrleil in 1912, and Plant II, completed in 1916. PZach 
plant is served hy an individual hydro-electric power station 
111 i.pjajun electrical horsepower capacity. The water for 
Ihnver riiiuse T is brought to the turbines from a lake high 
up ill ihe mciuntains and three miles distant from the power 
house, thrciogh a number of steel tubes or conduits in par- 
allel. Hie spent water from this station is then led through 
a rurk tunnel cut in the mountain, a distance of miles to 
Power IlciLise II. In addition to the hydro-electric gener- 
ating ecjLiipment, eacli power station operates three steam 
driven Uirho-generators of a rated capacity of 13,000 elec- 
trical horsepower each. The steam for these generators 
is supplied by the waste heat boilers for cooling the nitrogen 
oxide eontaiiiing gases leaving the arc furnace. 

In the are furnace room of Plant I there are installed 120 


SchonheiT furnaces of i,ooo kilowatts capacity each, and six 
of the earlier Birkeland-Eyde type of 3,500 kilowatts capac- 
ity each. At Plant II are 36 BItkeland-Eyde furnaces. 
The SchonheiT furnaces, to satisfy the demands for the long 
slender arc, are 30 Inches In diameter by 25 feet In length. In 
the new Birkeland-Eyde furnaces, as of Plant II, an alternat- 
ing current arc Is maintained between water-cooled copper 
electrodes which are placed between the poles of an electro- 

Yoke of 

Edge FuiInace 

magnet, so that the direction of the arc Is at right angles to 
that of constant magnetic field. This furnace Is Inclosed 
within a steel cylindrical case, 12 feet In diameter by 5 
feet between the flat ends. The Inner surface of this casing 
is lined with fire brick leaving a cylindrical space 6 feet In 
diameter by 6 Inches thick In which the arc expanils. The 



air enters this arc region through perforations in the brick 
wall and leaves through openings along the circumference 
of this region. The capacity of these furnaces is 4,000 kw. 

Although the furnace rooms of the two plants are about a 
mile apart the absorption buildings are adjacent and in the 
immediate vicinity of the furnace room of Plant I. This 
makes it necessary to convey the gases as they leave the 
economizers of Plant II a distance of nearly a mile. In 
traveling this distance through 5 aluminum tubes, each 3 
feet in diameter, the gases are cooled from 200° C to about 
50° C, obviating the necessity of a cooling tower. Further, 
upon cooling, oxidation of the nitric oxide takes place so 
that the gases upon reaching the absorption building are 
drawn directly into the absorption system. 

The absorption towers which are of granite are 22 feet in 
diameter by 70 feet high and are arranged in sets of four 
each. The furnace gases entering the base of tower No. 4 
pass up through this tower to the base of tower No. 3, and 
so on through this tower and through towers No. 2 and 
No. I. From the exit of tower No. i the gases pass in series 
through two alkaline towers from which the unabsorbed 
nitrogen oxides pass to the atmosphere. The absorbing 
liquid hows through these towers counter-currently. Water 
sprayed from the top of tower No. i absorbs some of the 
nitrogen oxides on its descent. The weak nitric acid from 
the base of this tower is pumped to the top of tower No. 2 
and so on, through tower No. 4, where the acid reaches 30 
per cent strength. 

A product of this plant, but not necessarily a product of 
the arc process, is calcium nitrate or Norwegian saltpeter. 
This salt is produced by treating limestone with nitric acid. 


A use for some of the steam of the waste heat boilers is 
presented here for evaporation to concentrate the solution 

Granite Towers at Rjukan Pj-ant for Absorp- 
tion OF Nitrogen Oxides 

to 13 per cent nitrogen. Calcium nitrate is used for fer- 
tilizer purposes. 

The Pauling furnace is operated in a plant of 1,000 tons 
of nitrogen annual capacity at Patsch, near Innsbruck, 
Austria. In this furnace the arc passes between two water- 
cooled, cast-steel tubular electrodes, which are set perpen- 



dicular to each other and in a vertical plane and spaced 
about two inches apart. The arc lias the appearance of a 
vertical sheet of Hame extending between the electrodes. 
The gas leaving the furnace at 1000° C is cooled in a pre- 
heater and ill a cooling tower packed with fire brick before 
the gas reaches tlie steann boilers. The capacity of the 
Pauling furnace is 800 kilowatts. 

Ill an operation in which the efficiency of energy utiliza- 
tion is so very low the margin of conceivable improvement 
is great. Such a condition leads naturally to intensive re- 
search and development. The results of these investiga- 
tions with small-scale furnaces have invariably indicated 
marked improvements in the efficiency of energy utilization. 
This increase in efficiency gradually diminishes with an in- 
crease in the size of the furnace used, until it has disap- 
peared entirely when a size of furnace which might be con- 
sidered commercial has been reached. 

The use of oxygen-enriched air, to the extent of a 50— 50 
ratio of nitrogen to oxygen gave some promise of increased 
yields. In such a system, howewer, economy in the use of 
oxygen necessitates the return of the gas to the furnace after 
the absorptinn of the oxides. Preheating the air entering 
the furnace has also been tried but it has been found that 
any advantage gained througii such ptciieating has been 
lost through increased decompositiun of the nitric oxide. 
Operation of the arc under a pressure of several atmos- 
pheres has not given enough promise of improvement to 
warrant large-scale experiments. 

The possibility at this time far marked improvements in 
operation efficiency is not hcipeful and there are indications 
of the are process giving way ta the direct synthetic ammonia 

Chapter IV 


In the cyanamide process gaseous nitrogen is fixed by 
bringing it into contact witli finely powdered calcium carbide 
heated to 1000° C. Tliis formation of calcium cyanamide is 
represented by the equation 

CaC^ -h K = CaCN, -h C. 

Ill producing the two reacting materials, extremes of tem- 
peratures are employed. Calcium carbide is produced by 
means of the intense heat of the electric furnace, while the 
nitrogen is secured through the fractionation of air which 
has been liquefied at a temperature of 190'’ C below zero. 

The production of calcium cyanamide invulvcs four steps: 
(i) The production of lime from limestone; (2) The pro- 
duction of calcium carbide; (3) The production of gaseous 
nitrogen; and (4) The nitrification of the carbide. 

Ill the first step, crushed limestone is burned in a kiln at 
a temperature nf 1100* C until the carbon dioxide has been 
driven oft. This process is represented by the equation 

CaCOs = CaO + COf — 42,900 gram, calories. 

and may be carried out in either a rotary or vertical kiln. 
In the rotary kiln the limestone rock is fed into one end of 
the kiln which is so inclined that upon rotation the limestone 
flows slowly down its length. The fuel, dried and finely 
pulverized coal for instance, is introduced through a burner 




at this lower end. The rock is gradually decomposed and 
the liberated carbon dioxide is carried away with the fur- 
nace gases, by means of a stack. The burnt lime is dis- 
charged at 1 100° C to a cooler from which it is conveyed to 
storage. In this cooler, which maybe a rotary kiln usually 
of smaller diameter and length, the temperature is reduced 
to about 200 ° C. Since for the production of calciuni car- 
bide limestone of one inch diameter lump is preferred, there 
is a large quantity of hnes, perhaps as much as 2.5 per cent 
of the total. These fines are waste so far as the cyanamide 
process is concerned, but may have a value as agricultural 
or building lime. 

The production of calcium carbide is the power consum- 
ing operation of the cyanamide process. The carbide is 
formed by fusing a charge of a mixture of lime and carbon 
in the ratio of approximately 1 ,000 pounds nf carbon to 600 
pounds of coke in an electric furnace. TJie reaction is as 
expressed by the equation 

CaO -j- 3 C = CaC‘2 CO — 121,000 gram calorics. 

The carbon may be introduced as anthracite coal, char- 
coal or coke. The latter has proved preferable, however, 
and is by far of widest use in tins industry. It slionhl he a 
soft burned rather than metallurgical coke and of about 
three-fourths inch in size. It should contain at a maximum 
6 per Cent ash and 0.5 per eent moisture. 

The earbon monoxide formed, which amounts to about 
735 pounds per ton of crude carbide, is not recovered, al- 
though it has a heating value of 4,380 B.T.U. per pound. 

The furnaces are usually rectangular in shape, 5 feet or d 
feet deep, with the depth below the operating lloor, so that 
the carbide may be tapped from the furnace at the lower 



floor. The carbon electrodes, usually t’wo feet square each, 
are clamped three together in such a way as to give the ap^- 
pearance of one big electrode 2 feet by 6 feet. These elec- 
trodes six feet long are suspended above the furnace in 
such a manlier that their depth in the charge is automatically 
regulated by a solenoid which controls a motor-driven hoist. 

After the current to the electrodes has been turned on, the 
mixed charge of lime and coke is shoveled around the elec- 
trodes, the depth of charge being such that the top or visible 
layer is never thoroughly fused. In the fused state, the 
lime reacts with the carbon to produce molten carbide. 
The furnace is tapped at intervals of perhaps 35 minutes by 
fusing the tap plug with a needlelike carbon electrode. As 
the carbide issues from the furnace at a temperature of 
2200° C, it is run into iron chill cars where it is allowed to 
cool for from one day to a day and a half. 

The material is an 80 per cent to 85 per cent carbide, con- 
suming in production about 3,000 kilowatt hours per ton, 
equivalent to approximately 3,600 kilowatt hours per ton 
of Too per cent carbide, when produced in a furnace approxi- 
mately 22 feet by 13 feet by 6 feet deep. 

The 99.8 per cent pure nitrogen necessary for the nitrifi- 
cation of the carbide is separated from the atmosphere 
through a liquefaction and distillation process. Either one 
of two systems is generally used, the Claude or the Linde. 
The cost of the nitrogen is exceedingly small as compared 
with its fixation cost. When nitrogen fixation is spoken of, 
the accent should be on the fixation, rather than the nitrogen 
from a cost consideration. 

When air or a gas is compressed the air heats up, due to 
its compression, necessitating intercoolers and aftercoolers 
on the compressor. When this air expands, the reverse 



naturally happens and the expanding air gives up heat or is 
chilled. Now if the intercoolers on the conupressor have 
cooled the air after compression to the same temperature as 
it was originally, a cooling effect can be produced. This is 
the principle of the air liquefier. 

In the Linde process the air is compressed to 3,000 pounds 
and simply expanded, while the cold expanded air passes in 
heat exchange contiguity with the warmer incoming air, 
thereby reducing its temperature. In the Claude process 
the compressed air is expanded in an expansion engine thus 
obtaining a cooling effect due to external work as well as 
to the simple expansion or Joule-Thompson effect of the 
Linde process. Because of this, the air in the Claude proc- 
ess is compressed to only 450 pounds originally, and 
a shorter time is consumed in reaching the liquefaction 

In the operation of the Claude Tiqi'e faction system, air 
which has been washed 111 caustic soda towers for the re- 
moval of carbon dioxide and passed through separators for 
the removal of caustic soda spray, is compressed to 450 
pounds and cooled in an aftercooler to the temperature of 
the cooling water, perhaps 20 ° C. It is then passed through 
two heat exchangers in series, where its temperature is low- 
ered through exchange of heat with colder outgoing ali% 
Most of the moisture of the air is condensed out here and 
collected in a purge bottle while any remaining together 
with any carbon dioxide which may not have been scrubbed 
out is deposited as a snow 011 the tubes of the second ex- 
changer, When this snow deposition is great enough to in- 
terfere with the free flow of air through it, the flow is auto- 
matically changed so that the order of the exchangers is 
changed. That is, exchanger No. 2 is now No. i, and re- 



ceives the air at the cooling water temperature, which, is 
high enough to thaw out the frozen tubes. 

From the second exchanger, 8o per cent of the air is ex- 
panded in the expansion engine and 20 per cent into the 
liquefierS. The temperature of the air drops from ~io8° C 
at the entrance to the expansion engine to —145° C at the 
outlet valve. The 20 per cent of the air which entered the 
I'lqueher is cooled "by gases from the rectifying column to 
the liquefying temperature. These two parts of air, 80 per 
cent as a gas and 20 per cent as a liquid, are both admitted 
to the bottom of die rectifying column which consists of a 
series of vertical tubes called vaporizer tubes, the lowet 
ends of which are submerged in the liquid. Due to the dif- 
ference in pressure at the bottom of the rectifying column 
and the space surrounding the tubes partial vaporization of 
the liquid takes place causing a liquefaction of the air in the 
tubes. This liquid from the base of the rectifying column 
is reintroduced into the column about midway between ends. 
This liquid is richer in oxygen than the original air. The 
uncondensed gas rich in nitrogen passes through the con- 
densing coil submerged in the litfuid which is cold enough to 
liquefy the nitrogen. This nearly pure liquid nitrogen is 
passed to the top of the rectifying colnmn from which nitro- 
gen gas of 99.99 per cent purity conies off at a temperature 
of —190° C and, after passing back through die liqueher and 
out through the tubes of the heat exchangers, is available for 
the nitrification of the carbide. 



1. Control valve of air elite rinf,’ tfXL’Iiaiiffer. 

2. Gauge fill' the prestiiire ilf the coiliji reused air slipplicd tu the apparatus. 

3. Vjlva f‘>i hiverliii^ the c‘i nip reused air circulatirm in the exchang;cr. 

^ Fi'oiii Fixation anil Utilization nf Nitrngeu, Report ^2041. 



4. Valve for inveiting llic oxygen and nitrogrii circulation in the ex- 


5. Valve for inverting the coinpress:;il air at Uie exit from llie exchanger. 

6 . Exchanger for cooling tlic iticnnimg air. 

6a. Drain fc-i p\nge. boitle fs.\' hanger. 

7. Exchabger for cooling the inonning air. 

7a. Drain valve for purge bottle of excluingc)’. 

8. Gauge foi' the piessnre of the connm;s;ei.l air .*)f ihe expoiision eogiue 


9. Control vtrivc for the expansion ciigiiir. 

10. Expansion engine for cooling air by exlel'iial avnrk, 

11. Liquefier for lii|uefactiiin uf air. 
iia, D-ain valve for tl|e liipiefier. 

12. Valve for throttling the liquid-air supply to &Lune pressure as ei)gii>L‘ 


13. Lowest cornpartincnt of rectifying roIiniDi. 

13a. Drain valvc for lowest conipartnieiit nf rrrlifyiog nilunni. 

13b. Watev level for the Uqnid iid\ irv ci>:ygel\. 

13c. Gauge for Ihc back picsshiv iti the hlwest cininiarlmeiil nf rectifying 

14. Vaporizer tubes for liqurfactinn of tb'r, 

14a. Mercury level of the vaporizer, 

14b. Oxygen pressure gauge. 

15. Valve for controlling tl]c upflow of tlic liqiiiil rirh in oxygen. 

16. Valve for the ohtk‘t of the impure pxygcii gas. 

16a. Cock for saiiniling waste oxygeii. 

>7* Coil submLTgeil in cooling lii|uiil fur liipicfiH'tinn of inffugen. 

17a. Cock for testing the plirity of iiifngi'ii leaving llie vapni' anil lining 
to the conilcnsiiig roil, 

18, Inlet to the rcetifyiiig rolumn iif rhe Hqniil rii'b in iixyg^'D, 

ig. Valvc to control tb* flow of li^ulii nitrn^cn tn the tup )if ihe Culr)ihi_ 

20, Top of the rectifying enUmii). 

20a. Water level for the lii|uiil pniir ih nxygeii. 

20b. Nitrogen press lire gali“e. 

2 oc. Cock for the nitriigen test. 

Before nitrification the carbide must be finely pulverzied 
so that at least 85 per cent nf it passes thrinigh 200 mesh 
screen. This necessitates a series of grinding operations 
following the breaking up 011 tfie carbide pig. In this pul- 
verized state carbide readily reacts with the moisture of the 
air to generate acetylene gas which forms explosive mix- 
tures with ojeygen. Because of this it is necessary to carry 
On these grinding and conveying operations in an atmos- 

Claude Process for Production of Pure Nitrogen Ga& 

phere of nitrogen. Frequent analyses are necessary, there- 
fore, to guard against greater concentrations of oxygen and 
acetylene than 2 per cent and i per cent, respectively. 

There are two types of nitrifying ovens in operation, a 
continuous and a discontinuous or batch type. Operation 




of the latter type accounts for at least 95 per cent of the 
cyanamide output of the world. In operation of the dis- 
continuous type a steel cylinder with perforated walls paper- 
lined and containing a pasteboard cone to provide an elec- 
trode space is filled with the finely ground carbide. This 
cylinder is contained in a gas-tight cylindrical oven. When 
the temperature within the oven has reached looo"^ C, nitro- 
gen is admitted and the electric current turned ofi. The re- 
action is then self-sustaining and continues for between 24 
hours and 48 hours, depending upon the size of the oven. 
The equation for this reaction is 

CaCa -h Na — CaCN2 -h C -h 98,430 gram calories. 

The energy consumption for this nitrifying operation is ap- 
proximately 1 15 kilowatt hours per ton of nitrogen fixed. 

Since the composition of the calcium cyaiiamide depends 
upon the quality of the raw materials and methods of oper- 
ation, it varies with different plants. The composition of 
the cyanamide produced at U. S. Nitrate Plant No. at 
Muscle Shoals, Alabama, was as follows: 

Per cent 

Calcium Cyanamide 61.2 

Calcium Oxide 20.0 

Calcium Carbide 1.5 

Calcium Sulphide .....0.2 

Calcium Phosphide 0.04 

Free Carbon. 12.5 

Silica 2.4 

Iron and Aluminum Oxides, ,1.8 

Magnesium Oxide. .0.2 

Upon completion of the nitrifying operation, the cyana- 
mide pig is removed from the furnace, cooled, broken. 



crushed, and finely ground in a manner and with equipment 
similar to that used for grinding the carbide. 

Since the presence of unnitrified carbide in the cyanamide 
is objectionable both for the production of ammonia and in 
fertilizer cyanamide, the finely ground material is sprayed 
with a limited amount of water in a closed hydrator from 
which the resulting acetylene gas is carried oft. 

The principal use for cyanamide is in agriculture as a 
nitrogenous fertilizer material. For this use however it is 
generally treated with additional water and briquetted or 
granulated and sometimes treated with oil to keep down the 

The product of this process after various stages of treat- 
ment is known by various names. 

Lime Nitrogen is the crude calcium cyanamide ground to 
a fine power after removal from the ovens. It is of the 
composition previously mentioned. 

Calchtm Cy-anamidc is the chemical compound as repre- 
sented by the formula CN.NCa or CaCN«. 

Cyanamid is a trade name for the completely hydrated 
material prepared for use as a fertilizer in the United 
States. It contains about 45 per cent of calcium cyana- 
mide CaCN., 27 per cent calcium hydroxide (slaked lime) 
Ca(OH)j, no carbide and various quantities of other ma- 
terials which might be called impurities. 

Nih'olini is the trade name for the material sold in Hng- 
land for agricultural purposes. It is a lime-nitrogen to 
which has been added just enough water to destroy the car- 
bide. Practically all free lime is present as calcium oxide. 

Kalksii^kstoff is the trade name for the material manu- 
factured in Germany for fertilizer use and is similar to 



As a fertilizer, cyanamide has several disadvantages, 
(i) It is a very disagreeable substance with which to work 
and is somewhat toxic to human beings if the material 
gets into the skin; (2) It cannut be used in large quanti- 
ties in mixed fertilizer containing acid phosphate owing 
to the natural reaction between the acid phospfiate and 
the cyanamide which causes the acid phosphate to revert 
and also may lead to the forniation of the agriculturally 
undesirable substance, dicyanodiamide; and (3) It has an 
inherent toxicity to plaiit growth greater than that of other 
fertilizer materials. This is particularly noticeable in dry 
seasons and prevents its use in as large quantities as other 
forms of nitrogen-contaiiiiiig substances. 

Through a process of autoclaving evanamide may be con- 
verted into ammonia. The cyanamide, or lime nitrogen, is 
introduced into an autoclave with water in the approximate 
proportions of four parts of cyanamide by weight to five 
parts of water plus a small amount of strong alkaline liquor, 
caustic soda, to aid the chemical reaction. The mixture is 
then treated with steam, and ammonia gas is released ac- 
cording to the equation 

CaCN, -p 3 HsO = 2 KH;, -h CaCOa. 

In operation, an autoclave of 6 feet diameter by 21 feet 
tall is charged with a filtrate liquor of approximately 2 per 
cent sodium hydroxide (NaOH) to 9 feet depth. This is 
approximately 19,000 pounds of liquor. To this is added 
300 pounds of scida ash to bring the alkaline strength to 3 
per cent sodium hydroxide, and 8,000 pounds of cyanamide. 
The charge is aerated for 15 minutes to eliminate acetylene, 
phosphine and hydrogen sulphide as completely as possible. 
The charging door of the autoclave is then closed and the 



steam turned on to start the reaction. When the pressure 
within the autoclave rises to 60 pounds as recorded 011 the 
gauge the steam is turned off and the reaction continues un- 
aided. The ammonia outlet is then opened and ammonia 
with large volumes of steam is drawn off continuously for 
approximately three hours. During this time the pressure 
remains rather constant, but it finally drops to atmospheric 
pressure. The outlet valve is then closed and the steam 
once more turned into the autoclave for about 20 minutes, 
when the pressure will have reached 120 pounds per square 
inch within the autoclave. The steam is again shut off and 
the ammonia discharge opened. The reaction and conse- 
quent release of ammonia now continues for an hour and a 
half. The sludge remaining in the autoclave is discharged 
to the slurry troughs which feed the filters. 

This ammonia may then be oxidized to nitric acid, which 
may be neutralized with additional ammonia to form am- 
monium nitrate. Such is the proposed operation of the 
U. S. Nitrate Plant No. 2 at Muscle Shoals, Alabama. In 
order to give a clearer picture of the cyanamide process, 
there follows an equipment description of this plant, the 
only cyanamide plant in the United States. 

The U. S. Nitrate Plant No, 2 was erected as a war emer- 
gency measure for the animal fixation of 40,000 tons of 
nitrogen in the form of 1 10,000 tons of ammonium nitrate. 

The manufacturing plant occupies an area rectangular 
in shape 5,310 feet by 2,860 feet with the long dimension 
running north and south. With the exception of the liquid 
air production, the sequence of manufacture is from north 
to south. The raw materials limestone, coal and coke arc 
unloaded from a trestle at the north end of the manufac- 
turing area and started into the process. All materials 




from the unloading of the raw materials from the cars 
to the discharge of the finished ammonium nitrate from 
the grainers are mechanically handled by belt and screw 
conveyers, bucket eleviitors, electric traveling cranes and 

The lime-bnrning plant consists of 7 rotary kilns each 8 
feet in diameter by 125 feet long from which the calcined 
lime is fed to 7 rotary coolers each 5 feet in diameter by 50 
feet long. The rated capacity of these is 700 tons of cal- 
cined lime per day (24 hours) which is stored in four similar 
concrete silos of 250 tons capacity. Fuel for the lime kilns 
is prepared in two Fuller iiulirect-fired rotary driers, 42 
inches by 42 feet, and four Fnller-Lehigh mills. This plant 
has a rated capacity of 336 tons of dried and pulverized 
coal per day. 

Coke for carbide production is crushed in two crushing 
units of three sets of double crusher rolls each, and dried in 
four rotary driers 5^ feet diameter by 40 feet long. This 
prepared coke is stored in four concrete silos of 160 tons 

Carbide is produced in 12 furnaces 22 feet by 13 feet by 
6 feet deep of 60 tons of carbide capacity per day each. 
Each furnace has three electrodes 16 by 48 by 80 inches 
each, which weigh together with the cooling head 3,000 
pounds. The carbide Is crushed and pulverized in three 30 
by 42 inch Buchanan jaw crushers, three 10 feet diameter by 
48 inch Hardingc ball mills, and three 7 feet diameter by 
24 feet Smidth mills. 

The liquid air plant of a rated capacity of 12,800,000 
cubic feet or 300 tons of nitrogen per 24 hours receives its 
air through two 36 inch spiral-riveted intake pipes. The 
air is washed in 8 sets of scnibbers of two to a set. There 




are 15 three-stage compressors of about 1,200 cubic feet per 
mihute displacement and a discharge pressure of 600 pounds 
per square Inch. In operation the air is compressed to 450 
pounds and is delivered to 30 iiitrogeii column equipments 
from which the nitrogen produced is delivered to the cyana- 
mide ovens, one-quarter of a mile to the west, through a 30 
loch spiral-riveted pipe. 

In the cyanamide plant there are 1,536 nitrifying ovens, 
each of 2,000 pounds finished product capacity, arranged in 
1 6 rows of 96 ovens each. The maximum rated capacity of 
this plant is 750 tons of crude calcium cyanamide per 24 
hours. The cyanamide ingots after being removed from 
the ovens by electric cranes are cooled, and then broken by 
being dropped upon the inclined platform which serves the 
crushing equipment. After being crushed and pulverized 
in a plant exactly similar to the carbide crushing plant, 
the cyanamide is hydrated In three 36 Inch by 36 feet king 
hydrators of a capacity of 2,1 60 tons of hydrated cyanamide 
per 24 hours. 

The silo building between the cyanamide plant and the 
ammonia plant contains nine concrete silos of a capacity of 
475 tons of cyanamide each. 

The ammonia plant for the autoclaving of cyanamide is 
of a rated capacity of 16634 tons of ammonia gas per 24 
hours and consists of 56 autoclaves arranged in 14 rows of 4 
each. These autoclaves are 6 feet In diameter by 21 feet 
high and are constructed of welded steel plate of one inch 
thickness for the side walls and inches for the domed 
tops and bottoms. Each autoclave Is fitted with an agitator 
which revolves at ii j/ r.p.m., each set of 4 agitators being 
driven by one 40-horsepower squirrel-cage Induction motor. 

Steam for the autoclaves and for heating the plant build- 

Lime Nitroge:^ Ovei^s in which Calcium Carbide is Nitrified 




'I'HK CYANAMIDK process 


ings is supplied by a process steam plant of a total boiler 
capacity at 120 per cent rating of 3,950 horse power. 

After leaving the autoclaves the ammonia gas is washed 
and dried by being passed through a series of mud drums 
and an installation of 7 ammonia columns each 9 feet in di- 
ameter by 19 feet high connected by 14 inch pipe to 7 de- 
phlegmators each 7 feet 2 inches in diameter by 8 feet 3 
inches high and 7 condensers similar in size to the dephleg- 
mators. Prom the condensers, the ammonia gas is stored 
in two 60,000 cubic feet gas holders. 

The slurry from the autoclaves is treated in 4 steel slurry 
troughs, each of which feed 5 vacuum filters 6 feet in di- 
ameter by 3 feet, making one revolution in ^}A minutes and 
having a capacity of 23^ tons of sludge per hour. From a 
hopper the sludge is pumped to a waste dump by four 650 
g.p.m centrifugal pumps. The filtrate from each set of 
10 filters is pumped by three 200 gallons per minute centrif- 
ugal pumps to 8 open-top steel storage tanks 13 feet 6 
inches in diameter by 12 inches deep from which it is pumped 
as needed into seven steel filtrate measuring tanks. 

The caustic equipment for preparing the autoclave solu- 
tion consists of one lime-slaking tank, one liquid elevator, 
three reaction agitators equipped with air lifts and steam 
coils, three thickener tanks, three diaphragm pumps, one 
sludge tank, two 15 centrifugal pumps, one solution 
tank and line 200 gallons per minute centrifugal solution 

In the nitric acid plant there are 696 catalyzer units each 
consisting of a rectangular aluminum tower 14 inches by 28 
inches by 5 feet high. A frame near the bottom of the 
tow’cr holds the 80 mesh platinum gauze, 13 inches by 27 
inches, of OLOO3 inch diameter wire. The mixture of air 

48 FIXATION OF atmospheric NITROGEN 

and ammonia gas passes down through the tower over the 
heated platinum gauze and out through a brick flue to the 
coolers. There are 25 high temperature coolers, 90 inches 
in diameter by 12 feet long horizontal, steel tubular, marine 
type boilers covered with an asbestos coating. The 12 low 
temperature coolers are 25 feet by 36 feet by 7 high 
constructed of chemical brick with 5 passages so arranged 
that the gas passes the full length of each cooler 5 times. 
Projecting down into each of these 5 passageways are 4 
rows of 35 cooling tubes each (20 rows in all). 

The 12 oxidation towers, 15 feet by 31 feet 6 inches, by 
15 feet high are similar to the low temperature coolers, ex- 
cept that they do not contain cooling tubes. 

There are 24 absorption towers, 31 feec 6 inches, by 34 
feet 2 inches, by 60 feet high. Although these towers are 
built of brick they serve the same purpose as, and are very 
similar to, the absoi*ption towers previously described for 
the arc process plant at Rjukan, Norway. These towers are 
packed with 6 inch and 3 inch vitrified spiral rings. The 
acid liquor is raised to the tops of the towers by air lifts in 
acid wells. There are 120 of these acid wells 12 inches in 
diameter by 96 feet deep. For weighing the acid there arc 
twelve aluminum tanks each ii feet in diameter by 10 feet 
deep equipped with Fairbanks beam scales. There are 
also 12 closed storage tanks each 31 feet diameter by 10 feet 
high constructed of reinforced concrete of a total capacity 
of 3)5^® tons of 40 per cent acid. 

For the production of ammonium nitrate there are 4 ab- 
sorption towers Syz feet square by 30 feet high, built of 
acid brick and filled with spiral tile, 4 coolers, 7F2 feet by 
13 feet by 8 feet high, 4 neutralizer tanks, ii feet by 26 feet 
by 7 feet high; 4 supply tanks ii feet diameter by lo feet 



high; 1 6 settling tanks each i8 feet in diameter by 6 feet 
high; 12 Sperry filter presses and 4 filtrate tanks, 18 feet in 
diameter by 6 feet deep. 

The ammonium nitrate liquor is stored in eight steel 
tanks 20 feet in diameter by 18 feet high and pumped from 
these to the 12 feet diameter by 12 feet high supply tanks 
serving each of the 5 evaporating and crystallizing units. 
Kach of these units consists of 10 enameled evaporating 
pans, feet by ii feet and 20 crystallizing pans and 
graiuers 5 feet in diameter by 18 inches deep. 

For maintenance purposes there is a fully equipped ma- 
chine, pipe and carpenter shop, a foundry and blacksmith 
shop. There is also a water supply system for domestic 
and fire purposes, consisting of a 60,000,000 gallon capacity 
reservoir, a settling basin of 300,000 gallon capacity, a filter 
plant of 1,500,000 gallons per 24 hours capacity, a clear 
water basin of a capacity of 500,000 gallons, and a pumping 
station of 44,420 gallons per minute. 

To give a somewhat clearer picture of the size of some 
of the buildings necessary to house the various equipment, 
it might be mentianeil that the carbide furnace building, 90 
feet by 1,050 feet by 64 feet high, if placed over the large 
Union Station in Washington, D, C., would completely en- 
velop it. The cyanamirle oven building is 250 feet by 520 
feet by 63^$ feet high. The liquid air building or nitrogen 
plant is 100 feet by 575 feet by 52^2 feet high, while the 
cooling and absorption building of the nitric acid group is 
200 feet by 600 feet by 90 feet high and has a ground 
area 10 per cent in excess of the United States Capitol 
building. The buildings of the manufacturing area have a 
ground area of 29 acres. 

The cyanamide process is now very well developed and 



little maybe expected by way of improvements. Some econ- 
omies of electrical energy consumption have been effected by 
increasing the size of the carbide furnaces and also of the 
nitrifying ovens. As can be pictured from the description 
of the U. S. Nitrate Plant No. 2, a cyanamide plant is a col- 
lection of previously well known operations, as for instance, 
lime burning, carbide manufacture, the liquefaction and 
fractional distillation of air, etc. It is rather natural then 
that the possibility of improvement of such a process is less 
than for a new operation such as the direct synthesis of 

Although over 95 per cent of the cyanamide produced is 
nitrified in the discontinuous type of oven, several continu- 
ous types have been tried. In one type of continuous fur- 
nace operated at Koapsack, Germany, carbide is placed in 
sheet-metal, collapsible boxes of about 3 cubic feet capacity. 
Au iron car on which have been placed 15 of these boxes 
runs on a track through a tunnel type of nitrifying oven. 
As a car is admitted to the tunnel a car containing nitrified 
material is pushed from the other end through heavy iron 
doors wTiich as far as possible exclude air from the furnace. 
The oven was heated by producer gas burned under the first 
third of its length and the nitrogen admitted counter current 
to the travel of the car. Many mechanical difficulties arose, 
however, due to the warping of the equipment from the heat 
of the furnace. 

In France at the Marignac plant, a somewhat similar and 
more successful attempt was made at the operation of a con- 
tinuous furnace. This furnace was equipped with caisson 
doors which minimized loss of nitrogen and dilution by air. 
This oven was heated by carbon pencils which extended 
from the sides a short distance above the carbide. 



The Stockholm Superfosfat Fabtik is operating still a 
third type of continuous oven in Sweden. The Swedish 
ovens are cylindrical towers containing shelves so arranged 
that the carbide charged in at the top moves cfownward 
friim shelf to shelf counter current to the flow of nitrogen 
which is admitted at the bottom of the oven. The heat re- 
quired to start the reaction is furnished by arcs near the top 
of the furnace. The nitrified carbide is discharged at the 
lower end. This is the only really continuous oven and is 
still in operation. 

It has been shown how ammonia may be produced from 
cyanamide. This ammonia may in turn be oxidized to ni- 
tric acid or it may he used to neutralize the various acids for 


the production of the ammoniacal salts. It may be ab- 
sorbed in water to form aqua ammonia or it may be com- 
pressed and liquefied for refrigeration purposes. Cyana- 
mide may also be a source of urea. In burning lime, large 
volumes of carbon dioxide gas are given off, which gas is 
utilized in the productiini of urea from cyanamide. Cal- 
cium cyanamide is fed uniformly into water pumped through 
a circuit with active agitation and the cooled lime kiln gases 
are blown into this circuit. The circulating liquid dissolves 
the carlniii dioxide nut of these gases forming carbonic acid 
which abstracts the calcium from calcium cyanamide forming 
Insohihle cahjum carhomiU and leaving in sohuioii free cy- 
anamide. A sniall quantity of sulphuric acid is added to the 
solution of free cyanamide which after about 12 hours of 
gentle agitation combines with water forming a 25 per cent 
sohitiDu of urea. This urea solution ‘s then treated with 
powdered calcium carbonate, converting most of the sulphu- 
ric acid to gypsum which is separated out in a iilter leaving 
a clear solution of urea. This clear solution is then evapO' 



rated in a vacuum pan in order to evaporate rapidly without 
using a temperature high enough to decompose the urea. 
The solution becomes a syrup and is tapped from the evap- 
orator when about 5 per cent of water remains. This con- 
centrated solution of urea may be chilled in a pan forming a 
slab of urea, or it may be atomized by a blast of cool air, 
producing the urea in a pellet form. Such urea contains 44 
to 45 per cent nitrogen. 

Although there is no cyanamide production in the United 
States, by far the larger production of the American Cyana- 
mid Company’s plant at Niagara Falls, Canada, enters this 
country either as cyanamide or crude cyanide. The cyana- 
mide is consumed directly in mixed fertilizers where it can 
be used in proportions of only about 60 pounds of cyana- 
mide to a ton of fertilizer, or it is autoclaved at the 
“ Ammo-Phos ” Works, Warners, New Jersey, for the pro- 
duction of ammonia for ammonium phosphate. The crude 
cyanide is used in metallurgy, in the production of hydro- 
cyanic acid for fumigation and the yellow and blue prusslates 
at the New Jersey plant. 

Cyanide is produced by fusing a mixture of cyanamide 
and sodium chloride in an electric furnace and quickly chill- 
ing the molten mass on completion of the reaction. The cy- 
anide is ill the form of calcium cyanide, Ca(CN)2, the so- 
dium chloride acting merely as a flux. 




The direct synthesis of ammonia from its elements, nitrogen 
and hydrogeni is expressed by the equation 

This reaction is accompanied by the evolution of 12,000 
gram calories of heat per gram mole of ammonia formed, 
which heat may be utilized in maintaining conditions neces- 
sary to continued operation. 

Such formation of ammonia, while very direct, is not 
quite as simple as the equation might indicate. Although 
ammonia can be synthesized at atmospheric pressure, the 
yield is so small as to be wholly impracticable. Further, 
while the percentage of ammonia at equilibrium is greater 
at the lower temperatures, commercially practicable oper- 
ation has not been attained at temperatures below about 
450*^ C. In fact, commercial operation is now carried on 
according to different methods of operation of the process 
at pressures varying from 100 atmospheres to 900 atmos- 
pheres and at temperatures from 450° C to 700° C. Even 
at these conditions of pressure and temperature, synthesis 
is practicable only in the presence of a catalyst. In prac- 
tice a mixture of three parts of hydrogen and one part of 
nitrogen is compressed and passed over a catalyst at an 
elevated temperature. The gas coming off the catalyst 




wilt tliL'ii be a mixture of byclrogcii, uitrtigeii and iimmcinia 
with ttie percentage of ammcuiia in the mixture ilepenilent 
upon the conditions of operation. As this mixture ap- 
proacIiCvS an equilibrium pnint, the maximum ([iiantlties df 
ammonia which may he present in tlie effluent gases af the 
converter are shown for various coiulitions of operadun in 
Figure Id 

i-in. I 

Tt will be noticed that a decrease in temperature has 
even a greater effect than an increase in pressure. Fur in- 
stance at 200 atmospheres and 600"' C the ecpiilihrhiin 
amiiuut of ammcinia is apprnxiinately >0 per cciitf while at 
the same pressure but at 400’' C, it is nearly 40 per cent. 
Nfdw, however, if instead of going dowO in temperature, 
the [iressLirc is increased to say 9110 atmospheres, the am- 
monia content increases to hut 30 per cent. It is evident 
then that the direction of greatest improvement Is in the 
development of a low temperature catalyst. The consid- 

Liirshi], Ti]£‘ A nil 1)1 mill Kijuilillnmll a! Hii^ii I’rt'sUiO'ii,” J. .Am, C hr ill, 

Sue, '/tit lf)7“7- (l‘>^•lJi. 


= 5 $ 

crable effart expended mi such an improvement has resulted 
ill the developiuenit of a catalyst w’hicli operates very 
satisfactorily at a temperature of from 450" C to 475*^ C. 
Ciiiitiiiueii effort may result in au even lower tempera- 
ture catalyst hut this will present other difficulties. As the 
temperature decreases the percentage of ammonia increases, 
and with it the i|uautity of heat liherated 111 the reaction, a 
sitiiaticiu which may well present the problem of taking the 
heat away fast eiuiugh to maintain the lower temperature. 
} luwrver, to civerciinie this, the pressure might be de- 
creased iir the llciw of gas over the catalyst increased, 
either of which or hath together would tend to decrease 
the cjLiantity of ammonia formed per pass, and hence keep 
the temperature dawn. 

It is readily seen then that the catalyst occupies a most 
ioiportaiLt place in the process. lu fact, it has been called 
the heart of the process and yet very little is known about 
it. It has been fouiid that iron oxide forms the best 
catalyst base kuiiwu at present, but the mechanism of its 
operation is not kiuiwii. Practically all of the operations 
today are by means of an iviiii base catalyst tci which 
has heeii added certain sahstaiices cidleil promoters which 
facilitate further the synthesis cif ammania, A catalyst is 
a material which aids a chemical reaction without itself 
entering pemiaueiitly into that reaction and, barring 
caiitamiiiaticin or physical nr mechanical destruction, 
shciuld have indefinite life. As a matter of fact it is 
known that under certain caiiclitions of operation a catalyst 
of the p rum cited iron type has maintained a high eflicieiicy 
for peri ails well over a year of contiimcd operation. 

Accfirding tci Lhiited States Patent 1,489,497, an active 
catalyst might he one consisting of 98 per cent of Iron, i per 

5 ^ 


cent of potassium oxide, and i per cci't uf ahiiiiiuum iixide- 
These added promoter materials may he varied, hci\vi‘\ ci\ 
from 0.25 per cent to 2 per cent in case iif putassuiiii iixidca 
and from 0.25 per cent tii lU per cent in case dl aiLiiniiiiiin 
oxide. Ill any case the base is the same; that is, iriiu initiulK 
ill the form of the oxide. 

To quiitc til is patent, sudi a cataly'^t ina^ be prepared as 
follows; ” Melt irciii in a ccirreiit id' oxy^eu su thal iiiidtcii 
iron Oxide is formed, or else melt iriin iixiilc. Intel this 
molten iriiii oxide stir a nuxture ciinsistinp; uf ap[iriixiiiintcl\ 
1 per cent of sodium or piitassium iixide and iijqinixiniatele 
I per cent of ahimhinm oxide nr sibenn diiixiLle. 'I’lie tiital 
weight of the proiiiiitcr mixture is thus apprnxiiuatidv i per 
cent of the total weight iif the mass of tlir catal\si nr cata- 
lytic material, ft will be niiderstuod that these respective 
proportions may be varied in acciivilaiice widi tfn* raiigrs in- 
dicated above; but wlicii aiiiriiii catalytir ageni is I'liipluvril 
and ammonia is the product tube uhtaiued, f Ini\e Iniiiid 
that the proportions just specified gi\ e a catal\st ur rai al\tir 
material that in general prodnres tlie nnisl satis fatlnr\ re^ 
suit. The mass prepared as stated is alliiwiMl tn nml and 
them brcikeii intn small ]iicces.” 

There are of eotirse iitlier materials whieli ninv lie nsisL 


111 some instances a natural inamietitL’ has mveii ixocid rr- 
suits. Tn otlier cases metals iitlier tlian pniassiinn and alu- 
minum Iiave [)roved sailsfactnry as pn mioters. 

As was shown hy tlie etpiilihriuin curves cmiiplrte runviT- 
sioii of the nitragen-Iiyclnigen iiiixiiirc to ainintiiihi raiiiint 
be ucliieved by a single pass uf tills mixture <1x1-1* the eatal\st. 
In fact, in practical operation tlie percentage of aniiinniia 
formed only appruaclies tliese eqciilihritoii amuncifs. As the 
rate of gas flow over tlie catalyst is increased, ilic piTceulage 

’vnii DiRi‘:cT sYNTiii-rnc amivic)Mia i’roukss 


of ammoiiiii fiirnicil decreases and falls further away from 
the e(|LiiIihriLiiii amauiits. I'lic percentaf>;e of aiiimania dieu 
is ilepciideiit upiiii tlie viihiiiie iif ^as per unit volume of cat£t- 
lyst s[iace per hiiur, nr space vclndty. h'or instance, if fnr 
every cuinc fin it iif catalyst there is a flaw of Ras per hour 
equivalent tii 20,0011 ruhie fret, £it niimial temperatures anil 
pressures, the space veliicity is 20,000. 

Fii;. II 

The percentage of aminoniit in the eflhieiit gases nl a par- 
ticular catalyst chainher api:rating at 475 ' C and at various 
S[iaec vchicitirs fnr the pressures ion, -^cm, (loo, i,uua and 
1^500 atmospheres was as slinwn in h'igurc II. Men: again 
the effect cif pressure is shown and in addition there us also 
shown the effect nf volnnir Iliiwof gas. If the curves were 
contiiineil up to a y.eni flow of gas the percentage of amninnia 
would he practically tlie ecmilihrium amounts. It is inter- 

FlX/VriON OF A'rMOt^l’lIKRlC NiTROC;i’.N 


est'ing to note that for 300 atmcispheixs aperiitiou, with a 

10.000 space velocity, this catalyst ga\'e ahuiit it; per ri:nt 
of ammonia 111 tlm exit gases. At the same [iri'ssifre Inn at 

100.000 space velocity, 10 per cent u| aniiniuiin \vns oh- 
tained» If one cubic fmit cif calulyst is niiisiilereil there is 
then a flow of 10,000 cubic feet of gas lea\aii” the rulaUst 
pel' hour, of which 25 p^'* cent or 2,5011 ruhir un fs 11 ni- 
monia, while in the ease nf the increaseil s[Uiec vehiriu, u! 
the 100,000 cubic feet cif gas leaving the ratiilysl per Inmr, 
10 percent or 10,000 cubic feet is aniiuonia. Il is 'Inai sera 
that for this caiisiilcratiiiii iihine there is a clecitlril inlvaii- 
tage in working away friim cquilibriuin cnnililiiiiis at least 
to this extent, tather than tinvatcls such riiiulitinn*^. 

There is quite a iHffereiice iif C)pinioii as lo the lUnsl prar- 
ticable space velocity. ’Phe great majuritv iii ilir plants 
now operating are enipluying a spare vrbidtv oi amiini) 
or less, while the Nitrcigen Prinhicls Cuiiiniittr iif iln* I’rit Isli 
Munitifiiis Inveiitiinis Dcp'artnieiil aihaicatiol a spaev vebu- 
ity of 150,000 or higher. I'liere are many inhiiiinujl inn- 
sideratitins to be taken into accmmlt huwevi't, in ileterininiitg 
upon a Space velucity, A low s[iace vehicilv will rnpiitr f>n' 
a certain aimnnuia proiliictinn a larger ratalysl unnaiiuT 
than will a higher space‘ velucity. h’cir iuHtanri\ in tlii* ex- 
ample previously cited. It was fnianl lliat the hniirh innem-- 
sion of ammonia was four times as great at iiin,ii)Ui >qi.ue 
velocity as at 10,000 space velocitv- Ohvimislv thru bin 
one-foLcrtli as much catalyst is iiccrssarv ivifli tin* hi’^h spare 
velacity as with the liiw, niicl lienee hut a fniirih nf a Lubtv 
foot container is reipiircd for the catitlvst fi>r iiio,ij>»i span‘ 
velocity as compared with one eiihie fiicit riiutaiiu’r im' the 

10.000 space velocity. With the high space vclncitv. 
ever, different thermal coiiilitiofis will be presentt cifaim- 



knowing the per cent of ammonia in the effluent gas and the 
space velocity can readily determine how much ammonia he 
should be producing, or knowing the quantity of ammonia 
being produced and the space velocity, he can determine the 
per cent of ammonia in the effluent gas. However, by 
simple analysis he can actually measure the per cent of am- 
monia in tlie effluent gas and as he must always have a check 
on the ammonia production he can easily determine from 
such a diagram the space velocity or actual flaw of gas 
through the system. 

The discussion so far has been of the simple system of 
passing a compressed mixture of three parts of hydrogen 
and one of nitrogen over a catalyst at an elevated tempera- 
ture. As was shown, the gas mixture is not completely 
converted into ammonia. In fact, only a smaller part Is con- 
verted. In some actual operations the per cent of ammo- 
nia in the effluent gas of the converter Is as low as 5 per 
cent. It can readily be imagined then that the uncombined 
gases cannot be wasted. They must be returned to the cat- 
alyst. This then is a further step in the process which now 
consists of passing a compressed mixture of 3 parts of hy- 
drogen to i part of nitrogen over a catalyst, removing the 
ammonia formed and returning the uncombiued gases to the 
catalyst for further ammonia formation. In order then 
that this process may be continuous, a fresh quantity of the 
mixed gas equivalent to the ammonia removed is added to 
the system prior to the return of the uncombined gas mixture 
to the catalyst. As a drop in the pressure of the gas mix- 
ture will occur in its passage through the equipment and In 
the ammonia removal, there is generally inserted in the re- 
turn system, before the converter a circulating pump for the 
purpose of boosting the pressure up to operating pressure. 

riii‘: DiRi'cr svx'rfiK/ric ammonia i’rockss Oi 

Tills then is the ilircct synthetic iiiiiniimia process for ifie 
lixiUinii Ilf ntmnspheric iiitrii^eiu 

I iere I'^iiiii the emplnisis slmuhl lie mi the hxaliim rather 
than iiii till* iiitniReii. Securing the free iiitra^Cu is a small 
part of tlie ciist, while the hyilrii^eii with which the iiitragcn 
Is li>:eil re[ircscnts apprcixlinately 50 per ceiR (if the total 
nisi Ilf the ainiiiiinia. 

There are tnilay a imiiiher of inetliOils of opeiaitinii of 
the ilireet synthetic aimniuiiu process, which of themselves 
have come tn he calleil processes. 1 11 all the various niethiiils 
nitrii^Cii is fixeil with hyilni^en as ammiiiiia In the presence 
of 11 catalyst. In one metliiiil, known as the Clauile Process, 
instead of the tincimihliieil phases being circulated hack to the 
original catalyst after the removal of the contained am- 
rnonia, they are passed to another catalyst In series witfi the 
first lliis Is but aniither method of operating the direct 
synthetic aimnoida process, however, ami does not really 
ciiiistitiite an iiiiliviihial process for nitrogen lixathui any 
11 lure tlniii do the Casale, h'auser and Other nietliiicls of 
(jperatiiin of this process. Operation, however, might he 
divided iiitii two general systems, the cyclic, where the un- 
conihiiii'il gases fiillnwiug the removal of the cinitaineil am- 
monia are ri.* circulated over the same catalyst; anil the se- 
ries, where thrsn gases pass over a iiiimher of eatalyst 
chanihers in scries with amimnila reiniival means after radu 

There art; two means of aminiinia removal in commercial 
practice, ahsnrption anil refrigeration. In the Ilrst method, 
water nr acpia aiiiiTniuia is piimpcal over a tower in which arc 
ascending the gases friiin the system at the operating pres- 
sure, 'The annnonifi gas is scnihbeil out of the Iiydrogeii- 
nitrogen mixture which is returned to the circulatory system 
while the absorbing liquid is trapped. By regulating the 



flow of water over the tower, any one of several conditions 
may be maintained. The quantity of water used in propor- 
tion to the ammonia content of the gas may be such that 
the resulting liquid is a strong aqua ammonia. Increases in 
the quantity of water used beyond this amount would result 
in the production of a weaker ammonia liquor while the use 
of less water would result in free ammonia gas being given 
off from the solution upon release of pressure. If regula- 
tion is so maintained that the quantity of water is such as to 
carry out complete removal of the ammonia and at the same 
time to produce a saturated solution at the operating pres- 
sure the optimum conditions have been reached, providing 
ammonia gas is desired. Release of the pressure will free 
all the ammonia up to the saturation point of the solution at 
atmospheric pressure. This saturated solution or aqua am- 
monia may then be pumped over and over again merely ab- 
sorbing and releasing ammonia. If aqua ammonia is desired 
as well as ammonia gas, regulation can be such as to have 
any percentage of the two from all aqua and no gas to all 
gas and no aqua. 

The second method, refrigeration, is in perhaps even 
wider use than scrubbing, at least from the consideration of 
the number of plants operating. In this method, the 
nitrogen-hydrogen-ammonia gas mixture under pressure is 
cooled, resulting in the liquefaction of a portion of the am- 
monia, dependent upon the temperature to which the gas 
mixture is eooled and on the pressure. Figure IV ^ gives 
^the volume percentage of ammonia remaining in the vapor 
phase in a 3 to I mixture of hydrogen and nitrogen satu- 
rated with ammonia vapor. If operation is at 300 at- 
mospheres and the cooling medium used chills the gas 

Larson and Black. Jour. Am. Chem. Soc, ^7, 1015 (1925). 


mixture to 15^ C, there will remain in the mixture returning 
to the ammonia converter per cent of ammonia. The 
difference between that syntliesized and that returned will 
have been collected as liquid ammonia. If, on the other 
hand, a cooling medium were used which would reduce the 
temperature of the gas mixture to say — 20 ° C, there 
would be Only i per cent of ammonia remaining in 
the gas phase, the difference being collected as liquid 

Timpero^ure "C 

Fig. IV 

ammonia. It is interesting to note the effect of pres- 
sure oil ammonia removal. At 0 ° C for instance the 
ammonia remaining in the vapor phase decreases from 
10 per cent at 50 atmospheres pressure to 6 per cent at 100 
atmospheres. The advantage obtained by going up to 300 
atmospheres, however, is not so marked and at this pres- 
sure there remains over 3 per cent of ammonia, while there 
is 2^ per cent at 600 atmospheres and over 2 per cent at 
1,000 atmospheres. 

Before going into the various methods of operation of the 



direct synthetic ammonia process in any detail, it will be well 
to consider the sources of nitrogen and hydrogen. 

At 20° C and i atmosphere, the density of a mixture of 
one volume of nitrogen and three volumes of hydrogen is 
0,02223 pounds per cubic foot. There will then be required 

^ . 2,000 ^ r /• , 

per ton or ammonia = 89,970 cubic reet or the 

^ 0*02 2 23 

gas mixture. If it is considered that lo per cent of the gas 
mixture is lost through leaks and purging, the original vol- 
ume of the nitrogen-hydrogen mixture for the produc- 

tion of one ton of ammonia will have to be 



100,000 cubic feet, of which 25 per cent or 25,000 cubic feet 
is nitrogen and 75 per cent or 75,000 cubic feet is hy- 

The largest source of hydrogen for the commercial fixa- 
tion of nitrogen according to the direct synthetic ammonia 
process is water gas. This gas results from blowing steam 
over a bed of glowing coke and has the following approxi- 
mate composition: 

H2 Hydrogen 50 per cent 

CO Carbon monoxide . .43 per cent 

CO2 Carbon dioxide .... 4 per cent 

N2 Nitrogen 2 per cent 

CH4, H2O, H2S, etc I per cent 

In the operation of the water gas generator after the bed 
of glowing coke is partly quenched by the make ” or steam 
blow, it is revived by an air blow. 

Use is made of the carbon monoxide content of the gas to 
effect the production of additional hydrogen. Water gas as 
it comes from the gas generator is treated with steam in the 


presence of a catalyst, usually iron oxide, at atmospheric 
pressure and at a temperature of about 500^ C. The car- 
bon monoxide of the water gas combines with the steam to 
form hydrogen and carbon dioxide according to the equation 

CO H .0 = Ha -h CO2. 

This reaction is exothermic, liberating at 500° C approxi- 
mately 10,000 calories per mol of carbon monoxide reacting, 
which is sufficient heat to maintain the temperature. From 
a hundred parts of water gas there Is obtained in this way 
about 90 parts of hydrogen. 

The gas as it comes from the carbon monoxide catalyst 
chamber contains after condensation of the steam about 45 
per cent of carbon dioxide and 3 per cent of carbon monox- 
ide, the remaining 52 per cent being hydrogen from which 
tnese other gases must be moved. The larger part of the 
carbon dioxide may be removed by scrubbing with water. 
This is usually carried out at a pressure of 30 atmospheres 
or more. The remaining carbon dioxide, two per cent or 
less, is removed by scrubbing with caustic solution. The 
traces of carbon monoxide remaining in the gas are removed 
by scrubbing with a cuprous ammonium formate solution. 

The necessary nitrogen for ammonia synthesis may be 
produced as lean or producer gas, a gas produced by blow- 
ing air over glowing coke. This producer gas is of a com- 
position of about 

H2 Hydrogen 10 per cent 

N2 Nitrogen 60 per cent 

CO Carbon monoxide ..25 per cent 
CO2 CH4 Carbon dioxide, 

etc., methane, etc. 5 per cent 



In order to obtain the desired mixture of 3 parts of hydro- 
gen and I part of nitrogen, approximately two volumes of 
water gas are mixed with one volume of producer gas. This 
mixture is deficient in nitrogen, which deficiency is made up 
by the addition of free nitrogen, procurable through the 
liquefaction and fractional distillation of air, in order to 
keep accurate control of the composition of the mixture. 

As an alternative to this mixing of the water and pro- 
ducer gases which had been made separately the mixture 
could be made directly in a water gas generator by admit- 
ting air to the glowing coke along with the steam blow. 
Due to difficulties of this operation, it has not found favor 

Another source of hydrogen In which coal plays the prin- 
cipal part is coke oven gas. The gas as it comes from the 
by-product coke o\'en is composed of approximately 

Hydrogen 55 per cent 

Methane 30 per cent 

Carbon monoxide 6 per cent 

Carbon dioxide 2 per cent 

Ilium in ants 3 per cent 


The hydrogen is removed from this mixture by the lique-"" 
faction and fractional distillation process. 

Although electrolytic hydrogen is ideal for ammonia syn- 
thesis because of its purity it accounts for only 15 per cent of 
the ammonia produced by the direct synthetic ammonia proc- 
ess. The capital cost of a plant for the electrolysis is high, 
and except for a few especially favorable locations, electri- 
cal energy is more valuable for other industries. Although 
better results are claimed for certain cells, experience shows 
that the larger Installations in this country have consumed 


140 kilowatt hours per 1,000 cubic feet of hydrogen. The 

5.000 ampere cells, such as are in operation in the United 
States at 2.24 volts, consume 268.8 kilowatt hours for the 
production of 1,920 cubic feet of hydrogen per 24 hours 
each. These cells contain about 150 gallons of water In 
which is dissolved 435 pounds of 88 to 92 per cent potassium 
hydroxide. The cells operate on direct current, necessitating 
in most cases the conversion of alternating current, usually 
by means of a motor generator set, although rotary con- 
verters are sometimes used. 

Hydrogen is also obtained as a by-product in a number of 
electrochemical processes such as the production of caustic 
and chlorine. Although the total volume of such hydrogen 
is very large the quantity available at any one location is 
relatively small, a ten ton per day ammonia unit being the 
largest plant operating on such waste hydrogen- 

The fermentation of corn for the production of " buty- 
nol,” butyl alcohol, is a further source of hydrogen. The 
Commercial Solvents Corporation has been wasting over 

1.500.000 cubic feet of such hydrogen per day at two 
plants at Terre Haute, Indiana, and Peoria, IHiuois. Dur- 
ing the spring of 1927, a direct synthetic ammonia plant of 
1 2 to 15 tons of ammonia per day capacity was started into 
operation to utilize this otherwise waste hydrogen. This 
plant was later utilized for the production of synthetic 
methyl alcohol (methanol), thus utilizing both the previ- 
ously wasted hydrogen and carbon dioxide. 

There are also millions of cubic feet of hydrogen going 
to waste from natural gas wells. At Monroe, Louisiana, at 
the carbon black plant of the Thermatomic Carbon Com- 
pany some 10,000,000 cubic feet of hydrogen containing 
about 6 per cent of methane is being wasted daily. Ibis 



source of hydrogen has been investigated by a large number 
of industrial concerns. There are several objections to this 
source, however. The removal of the 6 per cent of meth- 
ane presents a serious problem, while the doubtful life of 
this supply greatly magnifies the risk of a large investment 
such as would be necessary for the utilization of all this hy- 
drogen for the production of synthetic ammonia. 

Another source of hydrogen of promise is that of the so- 
called LUjenroth Process. In this process elementary phos- 
phorus LS produced in an electric furnace from phosphate 
rock, silica and coke. A mixture of phosphorus vapor and 
steam is then passed over a catalyst maintained at about 
700° C, producing phosphoric acid and hydrogen. 

The principal reactions are represented by the equations: 

2 Cas(P04)2 "h 6 S1O2 -h 10 C = 6 CaSiOs -H 10 CO 

P4 -b 16 H2O = 4 H3PO4 -b 10 Ho. 

In carrying out the latter reaction on a commercial scale, dif- 
ficulty is experienced in preventing the formation of phos- 
phine according to the following equation: 

P4-b 12 H2O = PHs-b 3 H3PO4 -b6H.. 

The importance of such a source of hydrogen for am- 
monia production lies in the value of phosphoric acid, a plant 
foodi as an ammonia carrier. A plant for the production of 
phosphorus according to this process is in operation at the 
cyanamide plant at Piesteritz, Germany. The phosphorus 
produced is shipped to the Badische AnIIIn und Soda Fabrik 
at Merseburg, where it is oxidized with steam to phosphoric 
acid and hydrogen. ‘ ' 

In addition to the producer gas method for nitrogen pro- 
duction, nitrogen may also be separated from the air by the 


Hquefaction-distillation method described In the chapter 
dealing with the cyanamidc process, or hydrogen may be 
burned In air to combine with the oxygen to form water, 
leaving the nitrogen. In this latter method, by admitting 
the hydrogen In sufficient excess of that required to remove 
the oxygen, the resulting gas mixture may be adjusted to 
contain three parts of hydrogen to one part of nitrogen. 

If the composition of the air is considered as being 

Nitrogen .78.14 per cent 

Oxygen 20,92 per cent 

Argon 0.90^ per cent 

- Others 0.14 per cent 



there will be required ^ — = 22,000 cubic feet of air to 

^ 0.7814 

produce the nitrogen required per ton of ammonia. 
From this amount of air there wiU be 32,000 X 0.2092 
6.1690 cubic feet of oxygen to be disposed of, requiring 
131380 cubic feet of hydrogen. The total hydrogen re- 
quirements per ton of ammonia for a plant obtaining its ni- 
trogen in this way will be 75,000 -|- 13,380 = 88,380 cubic 
feet measured at 20^ C and i atmosphere. 

The flow diagram shown In the frontispiece and the model 
of a complete equipment assembly. Figure V, give a clearer 
picture of the direct synthetic ammonia process In commer- 
cial plant operation. 

In the model, hydrogen, produced by one o£ the methods 
previously mentioned, is brought into the plant by means of 
main i. It passes through blowers 2j where its pressure is 
increased to 2^^ pounds per square Inch, to burner 3. Air 
is introduced to the burner 3 through main 4 and blower 5, 



in which its pressure is raised to pounds also. In the 
burner the hydrogen and air mix and come iii contact with 
a spark. Combustion then takes place with the formation 
of w'ater which is removed in condenser 6, the residual gases 
passing out to a gasometer tlirough the mixed gas main 7. 
By proper regulation of the flow of hydrogen and air to the 

Fic. V 

Model of a Direct Synthetic Ammonia Plant 
burner, the gas coming off the condenser can be maintained 
as a I to 3 mixture of nitrogen and hydrogen, which is the 
ratio of these elements in ammonia. 8 is a control board, 
containing the volume gauges indicating the flow of gas to 
the burner, and the valves for regulating this flow. 

From the gasometer this mixed gas (N2 + 3 H2) is drawn 
through main 9, to the compressors to, where, in this system, 
it is compressed to 300 atmospheres. The compressed gas 

THE direct synthetic AMMONIA PROCESS ~t 


then passes on through oil traps 1 1 for the removal of com- 
pressor lubricant to the purifier 12. This purifier contains 
a catalyst which while not an efficient ammonia catalyst is 
not easily poisoned. Only a relatively small percentage of 
ammonia is formed in this purifier. This is condenseil 
Out in the condenser 13 and collected in receiver 14. The 
ammonia in condensing out of the gas picks up any contained 
water and water vapors, leaving the residual gas which had 
been purified of other catalyst poisons in the purifier, pure 
and dry. When a sufficient quantity of liquid ammonia has 
been collected in receiver 14, it is unloaded to receiver 15, 
which when shut off from 14 is subjected only to the vapor 
pressure of ammonia. It may then be safely unloaded to 
lower pressure equipment. 

From receiver 14 the gas after dropping the liquid am- 
monia passes through converter 16. In this converter, 
which contains the ammonia catalyst, synthesis takes place, 
resulting, at 300 atmospheres and 475° C, in the effluent 
gases containing 20 per cent of ammonia. 17 is the control 
panel containing pressure gauges, temperature recorders 
and purifier and converter control. From the converter the 
gas mixture (N2 -h 3H2 T 20% NH^) flows through con- 
densers 18, where a small amount of ammonia is liquefied 
but not removed. Due to friction in passing through the 
catalyst mass and subsequent equipment, the gas pressure 
has dropped and so must be boosted up to the original oper- 
ating pressure in order that the uncombined gases may he 
recirculated through the converter. As this gas is at this 
stage pure and dry, it is desired not to contaminate it by ad- 
mitting oil or other such lubricant to the circulating or boost- 
ing pump. This mixture of (N2 -|- 3 Hs -h gaseous NH^. -|- 
liquid NH3) from the condensers 18 is admitted to the cir- 

Ftg. VI 

Hyduocen-Air Burn 


culatiiig pump 19, where the liquid ammonia acts as the lu- 
bricant. The flow is tiien through the condensers 20 to re- 
ceiver 21, where the liquid ammonia is collected while the 
Lincombliied gases pass on to meet the make-up gas at the 
entrance to the converter. From receiver 2 1 , the liquid am- 
monia is unloaded to receiver 22, from which it is unloaded 
to the low-pressure storage 23. From this storage, a part 
of the ammonia goes to accumulator 24, which maintains the 
level of the ammonia in the condensers 20. The expanded 
ammonia from the condensers and the surplus ammonia in 
the storage Is then piped ofl to the ammonia conversion or 
utilization plant. 25 denotes water pumps for the supply 
of cooling water to the burner condenser 6, compressors 10 
and condensers 13 and 18. 

The hydrogen-air burner shown in the model as 3 is 
shown in cross sectional detail in Figure VL Mydrogen 
and air are admitted separately, as shown, and meet at a 
point about midway of the length of the body of the burner. 
Here by means of a spark jumping from an extended lead of 
a spark plug, the hydrogen-oxygen mixture is ignited. The 
spark of course is necessary only on starting up, after which 
burning continues unaided and the nitrogen of the air, to- 
gether with the excess hydrogen, is collected. Each volume 
of oxygen combines with two volumes of hydrogen to torm 
water, which is removed in the condenser following the 
burner. The gas mixture from the point of combustion 
flows down into the mixing chamber and up through the 
cracked porcelain and shredded copper or copper turnings 
heated to an elevated temperature by the heat of combus- 
tion, and out. The burner operates under 2 pounds pressure 
which is supplied by positive pressure-blowers. The hydro- 
gen blower should preferably be liquid sealed. Hydrogen 



and air are admitted to tfie burner in such volumes that the 
effluent gas mixture is in the ratio of 3 parts of hydrogeii to 
1 part of nitrogen. These volumes will he in the ratio of 
I volume of air to 2.75 volumes of hydrogen. 

The mixture in the burner is controlled by regulating the 
volume delivered by the hydrogen and air blowers. Since 
a definite mixture of hydrogen and air at standard conditions 
of atmospheric barometer and temperature is required, Ven- 
turi meters may be placed before the blowers. 

The gas densities of various parts of the system are of 
interest and importance to the designing engineer. If con- 
ditions of operation are such that of 100 volumes of gas 
leaving the converter, 20 volumes are ammonia and that 1 5 
volumes of ammonia are removed by refrigeration there will 
then be 80 volumes of the gas mixture (Ni- -)- 3 TT) plus 5 
volumes of ammonia to be recirculated. Since it requires 2 
volumes of (N. -h 3 H^) gas to make one volume of ammo- 
nia (NH3) the 15 volumes of ammonia removed must be 
replaced with 30 volumes of make-up gas. The gas enter- 
ing the converter will then be 115 volumes, made up of 
(80 "h 30) or no volumes of (N2 -h 3 H^) gas and 5 vol- 
umes of NH3 gas. 




(68° F and 14.7 pounds) or (20° C and i atm.) 

Where P = pressure in pounds per sq. ft. = (14.7 X I44) = 

V = volume in cubic feet 
R = 766 for hydrogen 

T = temperature, ° Abs. = 460 -j- 68 = 528. 

The densities of the separate gases are as follows: 

(Ha) Hydrogen = 

2116.8 XI j . 

^ 6 X 528 ° pounds per cu. ft. 


3 H2) = 4.25 X 0.00523 = 0.02223 pounds per 

cu. ft. 

(NH3) = 8.5 ^ ~ 0.O4446 pounds per du. ft. 

Gas entering converter 

iio Vols. (N*2 -h 3 Hi) — 95.6 per cent 
- /"VTTjr \ 4-4 (<■ 

5 Vols. (NHs) 

lOO.O ti 

95.6 X 4.^5 -h 4.4 X 8.5 

X 0.00523 = 0,02320 poLiiids per 

Gas leaving converter 

80 Vols. (Ni+ 3H2) _ 80 X 4-:^5 + :io X 8.5 
aoVols. (NHs) “ 100 Xo..^5.j 

0.02667 pouluis per cu. ft. 

The deviation of these gases at high pressure from the 
perfect gas or Boyle’s law Is also of interest and must be 
taken into account. Figure VffP- shows the compressibility 
factor for pure hydrogen, pure nitrogen and 75 per cent hy- 
drogen plus 25 per cent nitrogen for pressures from atmos- 
pheric to 1,000 atmospheres. 

If these gases obeyed the perfect gas laws, the compressi- 
bility factor curves would be simply straight, horizontal 


lines, through the point i.o and „ for 300 atmospheres 

-to Vo 

would equal i and = i. PoVo = 300. However, actu- 


ally for the (N^ -h3Ha) mixture ^ . ■ = 1.I9 and PoVo = 254. 


One volume of the nitrogen-hydrogen mixture in synthesis 
proportions at 300 atmospheres pressure will expand to 
only 254 volumes at atmospheric pressure. 

^ Bartlett, Jour, Am. Chcin. Soc. 687 (1927). 



O >00 200 300 400 SCO €00 700 SOO 900 fOOO 

Pre35ore m fiimospberes 

Fig. VII 

The following outline of calculations for a 4 stage com- 
pressor will give an idea of the effect of these variations 
from Boyle’s law on the proportioning of stage cylinder 
diameters for a (N2 -|- 3 H2) mixture discharging at 300 

4 / 

Pressure ratioj R = = 4.16 

Pg, = pressure of atmosphere = 14.7 pounds per square Inch. 


Pij Pi>j Pgj P4 = pressure at end ot 1st stiigCj 2nd stage^ etc, 

Ti, T25 Ts^ T4 = temperature at end of 1st stage, 2nd stage, 


Pl = R X Pa = 4-i6 X I4.7 = 61.2 pounds per 
sq. in. = 4.16 atm. 

P2 = R X Pl = 4.16 X 61,2 = 255 pounds per 
sq. hi. = 17.J atm. 

Ps = R X Pi = 4.16 X 255 = 1060 pounds per 
sq. in. = 72.0 atm, 

P4 = R X P3 = 4.16 X 1058,3 = 44IO pounds per 
sq. m. = 300 atm. 

From Figure VII it is found that the gas volumes are for 

4.16 atni. = 



atm. = 



atm. = 



atm. = 

"- 54-5 

Ti, T2, Ts, Ti before intercooler = 4.16'^"^ X 520 = 786° Abs. 

= 326“^ F. 

It will be assumed that the intercoolers and aftercooler 
bring the temperature of the gas in each stage down to the 
temperature of the inlet. Then, if Boyle’s law’ held, the 
diameter of the cylinders for the different stages would vary 
as R, and the work of compression would be the same for 
each stage. Since the gas does not obey Boyle’s law and 
since it is desired to equalize the’ work of the several stages, 
it will be necessary to proportion the cylinder according to a 
new ratio, R', based on the volumes for the pressures shown 
above. The effect of this will be to Increase the diameter 
of the last two stages. If such precautions for equalizing 
the work were not made, the pressure ratio of the first stages 
would have been increased, thereby lowering the volumetric 
efficiency and increasing the temperature rise in that stage. 
The corrected ratios will then be 

R’l = K.*2 = K. = 

R'. = ^ = 4-c8 





= 3*6 o 

Fora delivery of 215 cubic feet of gas per minute (equiva- 
lent to 3 tons of ammonia per 24 hours) at standard condi- 
tions, 30 inches barometric pressure and 60° F, a piston 
speed of 380 feet per minute, single acting, will be consid- 
ered. A clearance volume of 8 per cent would give a volu- 
metric efficiency of I ~o.o8 (4.16 ~ i) =75 per cent. To 
provide for leakage at packings, etc., for these higher pres- 
sures, a volumetric efficiency of 70 per cent will be assumed. 
The compressor should be equipped with clearance pockets, 
which will take care of over-capacity resulting from a pos- 
sible higher volumetric efficiency. The piston diameters 
then are : 

Piston area (less rod) X 380 _ 216 
144 X 2 0,70 

n- /I jv -15 X I44 X 2 

Piston area (less rod) = — =222 so. in. 

^ 380 X 0.70 ^ 

Area of 2.375 inch piston rod = 4.43 square inches 
Total area of piston = 237.43 square inches 

Diameter of ist cylinder = di = 
say 17.5 inches. 


0.25 X 3.I416 

= 17,4 incheSj 

Diameter of 2nd cylinder = do = 

0.25 X 3.1416 4.16 


8.43 inches^ say 8.5 inches. 




Diameter of 3rd cylinder = da = = 407 inches^ say 


4.25 inches. 


Diameter of 4th cylinder = d^ = — ^ = 2.20 inches, say 


a.25 inches. 

With an assumed stroke of 17 inches, the revolutions per 
minute will be: 

R.p.m. X “ X 2 = 380 = 135, 

A suggestion for the ammonia converter Is shown in Fig- 
ure VIII. The cool gas entering at the bottom of the con- 
verter shell travels up through the narrow annular space in 
immediate contact with the inner surface of the pressure- 
sustaining shell, to the top of the shell and through a series 
of holes in the baffle cylinder, as shown in the upper left-hand 
corner of the drawing. The flow then continues down 
around the outside of the coiled tubing of the heat inter- 
changing, where it picks up the heat of the hot outgoing 
gases within the tubes, through the small openings at the 
bottom of the exchanger, into the heating element well, 
down around the heating element, and into the catalyst cham- 
ber. The gas, after passing up through the catalyst mass, 
passes out of this chamber through the inside of the tubes 
of the heat interchanger, where it gives up its heat to the 
incoming gas, and finally, relatively cool, passes out through 
the common take-ofl in the head. 

The catalyst space required per ton of ammonia daily pro- 
duction, considering the effluent gases from the converter 
to contain 20 per cent of ammonia, of which 75 per cent is 
removed, as previously set forth, and assuming a 20,000 
space velocity, is 


Fio. VIII 

Ammonia Converter 


8 i 





= 0.72 cubic feet 

in which 115 = volumes entering couvcrtei't 30 “volumes 

as ammonia, and 

9^1^00 , , TT V 

— ~ volumes ot 3 H.;>) mix- 

ture per hour. 

The pressure-sustaining vessel is made up of a steel shell 
closed by means of a liead made gas-tight with a flat copper 
gasket, and held in place by the ring and bolts as shown. 
The buttress threads of the ring and shell are interrupted so 
that in dismantling It is only necessary after loosening the 
bolts to give the ring a one-twelfth circumferential turn in 
order to disengage the threads and relieve the head^ so that 
it may be lifted out. 

The material for the shell might preferably be of the 2.5 
per cent chromium, 0,18 per cent vanadium, 0.30 per cent 
carbon type of alloy steel especially for such parts as come 
in contact with the hot reducing ammonia gases> The bolts 
and bolt ring may be of a 3 per cent nickel steel. As the 
tensile strength of steels and alloy steels decreases markedly 
as the temperature is increased from 300"^ C, it is advisable 
to keep the converter shell below this temperature- It is 
for this reason that the cool gas in the case of the converter 
shown is brought into immediate contact with the inner walk 
In cases where it has not been practicable to keep the tem- 
perature of the shell down, it has been found necessary to 
use a nickel-chromium alloy of 80 per cent to 85 per cent 
nickel and 20 to 15 per cent chromium. 

The converter as shown is 16 inches inside diameter by 
about 6 feet tall. The wall thickness of the shell is 3 inches. 



For iigurlug such tiuck-walled tubes, the use of a formula 
n,= n / I worked up in 1880 by Clavarino as a modi- 


ficatioii of the formula deduced by Lame in 1833, is still 
good practice. In tliis formula r<2 = outside radius, r^ = in- 
side radius, T = tangential stress, and R = unit internal 
pressure. For 300 atmospheres operating pressure and an 
allowable stress of 15,000 pounds per square inch, the wall 
thickness should be 2,80 inches. 

The gasket is a flat, uiiconfined copper ring, 0.125 
inches thick. The theoretical normal load, L required 
to keep the gasket from blowing and to seal the inter- 
nal gas pressure from leaking out with friction, F = 0.15 
would be the gas pressure against the edge of the gasket 


divided by twice the friction, 2F, or L = — • R has 
^ _ 0.3 

been found experimentally that a constant C ^ 2.5 must be 
introduced for regular close finish ” machining, because of 
the practical impossibility of machining absolutely perfect 
the surfaces between which the gasket is squeezed. This 


formula then becomes L = — X 2.5. To form a positive 


gas seal, a small V groove, equivalent to a continuous tool 
mark, is cut into the surfaces between which the gasket is 
compressed. The width of the gasket is such that the load 
applied by means of the bolts is at least 60,000 pounds per 
square inch causing the copper to flop and the groove is 
then filled with the flowing copper. 

The gasket for the converter is figured as follows: 

L = 440c X 0.125 X 2.5 _ 4580 pounds per inch of internal 
2 , X 0.15 length. 


To this must be added tlie load required to coutitcrbalance 
the internal gas pressure against the Iiead, as the gasket is 
made up before pressure is put on the vessel. 

16.375 - X 7t/4 X 4400 _ 1 8, GOO pounds per inch ot internal 
16.375 ^ ^ length of gasket. 

The total load per inch lengtli of gasket then becomt's 
4580 -\- 18,000 = 22,580 pounds and tlie widtii of gasket is 

-p = 0.3 8 inch- The width of the a;asket wall adjust 

60,000 ^ ■' 

itself to any applied load greater than 60,000 pounds per 

square inch by flowing, thus increasing Its surface area and 

reaching the equilibrium point of 60^000 pounds per square 

inch. It is well, for purposes of figuring the bolts and 

ring, to consider the gasket as being somewhat wnder than 

the actual figured whdth. If the width is taken as 0.5 

inch, the gasket area from the new diameter of 16.375 4" 0,5 

= 16.875 inches is 16.875 X tt. X 0.5 — 26.5 sq. in. 

At 60,000 pounds per square inch of surface area, the 

bolts must be able to stand 26.5 X 60,000 = 1,590,000 

pounds collectively- If fourteen bolts 2.25 inches in 

diameter with buttress threads are considered, each 


bolt must take ^ = 114,000 pounds, equivalent 


to --= 35,200 pounds per square inch compression 

at root of thread. This stress is transmitted bv means 
of the bolts to the ring and from this into the shell. 

The condensers for such a plant might be of the overflow’ 
type in which the hot gases pass downw’ard through several 
pipe coils in parallel, while w’ater or some other cooling 
medium entering at the bottom of the container surrounding 



the coils overflows at the top. They might also be of the 
flood type ammonia expansion in which liquid ammonia 
which surrounds the coils bolls off at the surface, the gaseous 
ammonia being carried to the utilization plant. 

The foregoing are a few' of the more important design 
considerations for a direct synthetic ammonia plant, regard- 
less of the method of operation. 

In Germany, where the process was first put to commer- 
cial use, operation is carried on according to the original 
patents of Haber. Hydrogen is produced by the water- 
gas catalytic method previously described, and often re- 
ferred to as the Bosch process, after its inventor. The two 
large Gei-man plants, one at Oppau and the other the 
’’ Leuna-Werke ” at Merseburg, are known as operating the 
Haber-Bosch process. 

At the Leuna-Werke which is located In the province of 
Saxony, about 100 miles southeast of Berlin, operation is 
carried out at 200 atmospheres pressure, ammonia is re- 
moved by water scrubbing and the uncombined gases are re- 
circulated back to the original catalyst for synthesizing. 

When this plant was producing In 1923 at the rate of ap- 
proximately 220,000 tons of fixed nitrogen annually, there 
w'ere employed, including the personnel necessary for the 
coal mining operations, 11,000 laborers, 2,500 operators, 
and 150 supervising cheTalste. and engineers,. Power was 
produced from brown coal from the company’s mines nearby 
and about 9,000 tons were required per day. At that time 
coke was used for the production of the hydrogen-nitrogen 
mixture and about 1,500 tons were required daily. The 
large quantities of water required, several thousand tons per 
day, were taken from the Saale River, about a mile distant. 

In this plant, 2 volumes of water gas were mixed with i 


volume of producer gas, giving a mixture of approximately 
35 per cent hydrogen, 20 per cent nitrogen. 40 per cent car- 
bon monoxide and 5 per cent carbon dioxide, methane, etc. 
This mixture was then treated as previously mentioned to 
convert tlie carbon monoxide witli steam to carbon dioxide 
and hydrogen, after which the composition w'as approxi- 
mately 17 per cent nitrogen, 52 per cent iivdrogen, 39 per 
cent carbon dioxide, and 2 per cent carbon monoxide. The 
bulk carbon dioxide was removed by water scrubbing at 
25 atmospheres pressure and the carbon monoxide by scrub- 
bing with cuprous ammonium formate solution at 200 at- 
mospheres. The traces of carbon dioxide reniaimng were 
removed by scrubbing whtli caustic solution. 

The catalyst used to effect the synthesis of ammonia is the 
iron base promoted type. Tbe converters are about 3J/2 
feet in diameter by 40 feet high. The steel casing 5 inches 
thick is perforated radially with inch holes spaced about 
a foot apart to release gases difiusing through the close ht- 
tiiig steel liner, 'which serves to protect the pressure vessel 
from the action of the gases. The effluent gases of the con- 
verter contain about 5 per cent of ammonia. 

The ammonia is removed by scrubbing the gas mixture 
with water. The uncombiiied gases are then returned to 
the converter by means of a circulating pump for another 
pass through the catalyst bed. 

In the Claude method operation is at 900 atmospheres, 
and synthesis takes place at about 700° C. There are 5 
catalyst tubes or converters, arranged with 2 in parallel, in 
series with 3 others in series. After each converter there 
is a condenser for the removal of the ammonia. If it is 
considered that 50 per cent of the gas mixture Is converted 
into ammonia at each pass and that 200 volumes of gas is 



used, this 200 volumes will be split, 100 going to each of the 
two coiivei'tefs 111 parallel. If 50 cent of each lOO vol- 
umes is converted into ammonia, there will remain after the 
ammmiia removal 100 volumes of tlie gas mixture to pass 
through the next converter. Likewise after the removal of 
tlie ammonia from this converter number 3, there will be 50 
volumes enterins; converter number 4 and then 25 volumes 
entering converter number 5. With 50 per cent of these 
gases being removed as ammonia, 1 2 volumes of the origi- 
nal 200 volumes remain to be returned tn the hydrogen 
puril'icatioii apparatus. 

The compressor for attaining the pressure of 900 atmos- 
pheres is of 8 stages arranged 5 on one side and the 3 high 
pressure stages on the other, of a tandem drive arrange- 
ment. Such a compressor for a 5 ton ammonia unit re- 
quires a 290 horsepower drive. 

The converters are about 6 feet long and i foot outside 
diameter. (Actually 2 meters high by 100 millimeters in- 
side diameter.) They are wound on the outside with mch- 
rome w'ire for temperature regulation and lagged on the 
outside. Here again an iron base catalyst is used; it has 
a life of only 300 hours. 

The steel tubing for the conveyance of the gases of a 
5 ton unit at this pressure, 900 atmospheres, is of a size such 

that — = ~ where d = inside diameter and D = outside 
D 22 


The Casale method of operation Is based upon thermal 
control of the ammonia converter. In order to eftect this 
control a certain percentage (supposedly one-third) of the 
ammonia formed is left in the gases returning to the catalyst, 
thus retarding the rate of conversion and In turn holding 
down the generation of heat. Operation is carried on at a 


pressure within the range of 600 atmospheres to 900 atmos- 
pheres and at about 500^ C. At 600 atmospheres, 500'' C 
and 12,000 space velocity, the effluent gases ot the con- 
verter contained 15 per cent of ammonia. The cataKst 
which is of the iron base promoted type Ims a life of about 
40 days. The converter w'hich for a 7 hi metric ton or S ^4 
net ton unit is about 20 feet high by 14 inches inside diam- 
eter contains about 10 cubic feet of catalyst disposed in an 
annular ring about 3 inches thick by 1 8 feet deep. The gas 
entering the converter through the bottom passes up along 
and in contact witli the inner surface of tlie shell and at the 
sanie time in heat exchange contiguity with the hot outgoing 
gases. It then passes dowm over an electrical heater con- 
tained in the core of the shell, up through the annular space 
of catalyst and down in heat exchange contact wdth the in- 
coming gases, and out. 

Another European development is that of Engineer Gia- 
como Fauser, This Fauser method developed in Italy fol- 
lows very closely the Haber operation, differing principally 
in some mechanical features. At 250 atmospheres pres- 
sure and 550° C to 600° C, 4 per cent of a.nimonia is ob- 
tained as measured in the gases leaving the catalyst. This 
ammonia is removed by scrubbing with aqua ammonia, 
which scrubbing medium is also used as the circulating pump 
lubricant or seal. 

There are a number of other developments. All, how'- 
evcr, are essentially modifications of the Haber method 
of operation of the direct synthesis ammonia process. In 
the United States It is understood that all the companies 
operating the direct synthetic ammonia process are 
licensed to operate under the original Haber patents 
which are controlled by the Chemical Foundation Incor- 

Chapter VI 


The pi'obability of fixed atmosplieric nitrogen products 
being able to compete successfully with Chile nitrate and 
more recently of Chile nitrate being able to maintain a posi- 
tion of importance in the face of the competition from the 
newer synthetic ammonia products have been questions of 
great concern not only to the nitrogen products industries, 
but to banking institutions as well. Bain and Mulliken, in 
Trade Information Bulletin No, 170, January 1924, ad- 
vise, ” It may be stated here that the present price of $48 
Eo.b. American Seaboard could, by abandonment of taxes 
(upon which the Chilean Government is dependent), by 
improved methods, and by the narrowest margin of profits, 
be reduced to about $35 per ton. This is not given as a 
probability, but the ultimate base figure which our fixed ni- 
trates must meet before the Chilean industry will cease to 

There is no doubt but that the fixed atmospheric nitrogen 
interests have given this serious consideration and are satis- 
fied of being able to offer competing products at an equiva- 
lent or even better price than this $35 figure. It is often 
argued that the new Guggenheim process which has been 
put into operation recently in Chile will so affect production 
costs as to restore Chile to its former position of importance 
in the nitrogen industry. However, it is reported that 
$30,000,000 was expended on this venture in Chile, for a 
producing capacity of 600,000 tons of nitrate per year. 



This Is equivalent to a capital investnaent ot $^o per annua' 
toil, which at 1 8 per cent capital charges for interest, amor* 
ti^ation, taxes and iiiSLiraucc adds $9 per ton to the cost 
of production. Taices and insurance at % per cent would 
amount to $i per ton, which might also be considered the 
charge for these items in the older officinas. As the invest- 
ments in these officinas have already been amortized, inter- 
est and amortization items need not necessarilv be carried. 


The new method then will be at a disadvantage of $8 per 
ton of exportable nitrate from the start and must produce 
at a cost of $8 less per ton before production by this method 
can compete evenly with the older officinas. Any reduction 
in cost greater than $8 per ton "will be that much to the ad- 
vantage of the new method. From this It can be seen that 
not too great an advantage for Chile nitrate is to be ex- 
pected from new methods of operation even though the old 
methods seem very crude. 

Perhaps the greatest advantage would be the reducing or 
total abandonment of the export tax of $12,30 per long ton 
of 96 per cent nitrate. Through this tax the world has 
supported the Chilean Government during the past 50 years 
to the extent of $900,000,000. It cannot be assumed, 
therefore, that in the event this tax was removed, nitrate 
would benefit to the extent of $12,30 per ton. Chile would 
have to make up this loss of revenue in some way, perhaps 
through increased import duties or other taxes which would 
affect nitrate production as well as other industries, so that 
abandonment of the export tax would not benefit nitrate to 
the full amount of the tax, and probably at best only to a 
small percentage of it, 

A comparison of some of the economic features of the 
atmospheric nitrogen fixation processes, the products of 
which are replacing Chile nitrate, will be of interest* 


Cafitfd co't 
per t,i nual 
of ni- 
trogs^y fixed 

1 hn-'>nediti)e 
fixed ni- 
■ trogen 


sumptwi'i //I 
ki/^br. per 
COJ) 0/ m- 

Raw nidtcr- 
ials re- 
quired per 
(till of 

Fir Si coiii- 

July, i)/_v, 
toy\s of 


j Operating 
! caparity 

ijufi, jpj?7, 




$ 6 oo 

Nitric 1 

6 1 tOno 




44 j 75° 


Cyanamidc 1 





^400 1 


Calcium | 



8 . 4 T 
Coke — 

2 51 T 
Coal — 
0.98 T 
179 lb. 




Direct Synthetic Ammonia 
with Electrolytic Hydrogen 




Steam — 

3 Tons 
Water — 

M cu. ft/ ‘ 
Air . 

1920 ■ 

1 17,000 ^ 


Direct Synthetic Ammonia 
with Water-gas Hydlogen 





Coke — 1 
Steam — 

1 1 Tons 
Water — 28 
M cu. ft. 

■ — ^ — i 



fp 1 




I In addition, there is installed 66,700 tons of nitrogen additional Capacity for operation by-product coke 
oven gas hydrogen and other by-product hydrogen. 



A glance at this chart shows that not only has intiustrial 
development in the art of fixing atmosplieric iiitrogea been 
in the direction of lower power consumption, but also in 
the direction of lower plant cost. This it w'ould seem is a 
natural course of development and indicates that the fixation 
of atmospheric nitrogen is developing along sound economic 

Because of the large power requirements of the arc proc- 
ess, developments of this process have been m the vicinity of 
large hydro-electric power sources. It is natural then that 
this process should be giving way to the direct synthetic 
ammonia process utilizing hydrogen produced by the elec- 
trolysis of water. With the electric power requirements for 
the fixation of one ton of nitrogen by the arc process, four 
tons can be fixed by the direct synthetic ammonia process, 
while the plant cost per annual ton of nitrogen is less than 
half that of the arc process. In addition, the product of the 
direct synthetic ammonia process Is of w’lder use than that of 
the ate process, Inastnnch as nitrk acid, the product of the 
latter process, can be produced hy conversion methods from 
the ammonia of the former process, w’hile this conversion 
cannot be reversed. It Is because of these considerations 
that the Norsk-Hydro of Norway is replacing its arc ca- 
pacity with direct synthetic ammonia capacity. It is expected 
that the total arc capacity will be abandoned and that such 
nitric acid as is required will be produced through ammonia 
oxidation. Nitric acid it is estimated can be produced at a 
lower cost by such a method than directly by the arc process. 
This synthetic ammonia development in Norway which is 
now under way, is apparently sounding the death knell of 
the arc process. 

In a like manner the cyanamide process, is beginning to 



undergo replacement by the direct synthetic ammonia proc- 
ess. In Sweden, the Stockholms Superfosfat Fabrik, the 
company operating the cyanamide process, is erecting a 
Fauser synthetic ammonia plant. Another Fauser direct 
syntlietic ammonia installation has been erected and is in 
operation at the cyanamide plant of the Mitteldeutsch 
Stickstoff Werke at Piesteriu, Germany. In Japan, the 
cyanamide process has already been replaced by both Claude 
and Casale synthetic ammonia plants. 

There will undoubtedly be some cyanamide production 
for some time to come, but the increase in capacity will be 
according to the direct synthetic ammonia process, resulting 
in a continually smaller percentage of the fixation according 
to the cyanamide process. Such shifts in location as the re- 
erection in Russia of the cyanamide units dismantled in 
Sweden to make room for synthetic ammonia capacity will 
tend to create the impression for a time of increase hi capac- 
ity, but the actual trend is a decrease. 

The reason for this shift to synthetic ammonia is a purely 
economic one. Nitrogen can be fixed in utilizable forms at 
a lower cost according to the direct synthetic ammonia proc- 
ess than by the other processes. 

If capital charges alone are considered, one advan^ge of 
the direct synthetic ammonia process oyer the other proc- 
esses can be seen immediately. If capital charges are |^ken 
at 18 per cent, these charges for the arc process amount to 
$108 per ton of nitrogen fixed, while for the direct synthetic 
ammonia process this charge would be $43.20 per ton, or 
$46.80 per ton according to the source of hydrogen. This 
is a disadvantage for the arc process of $62 to $65 per ton 
of nitrogen fixed. In like manner, cyanamide would be at 
a disadvantage of $26 to $29 per ton of nitrogen fixed. 



The effect of synthetic ammonia in the United States is 
very marked. Before the advent of the direct syntlietic 
ammonia process, liquid anhydrous ammonia was selliii^r in 
the Eastern states at 32 cents per pound in cylinders. Ei 
addition, it w’as the practice for the dealer to receive a 
deposit for tlie cylinder so that his investment was tied up 
only in those cylinders which were idle at his plant or ware- 
houses. At the present time this ammonia is being purchased 
by the Government on contract with the Mathleson Alkali 
Works at io }4 cents per pound in 100 pound cylinders^ 
delivered to point of consumption, and no cylinder deposit 
is required. In bulk, It has sold for as low as 6 cents per 

Probably because It is a relatively new industry, the com- 
mercial fixation of atmospheric nitrogen lias been sought 
out as the solution of various problems. Some of these 
problems, most of which can be answ’ered from the purely 
economic situation, follow: 

(i ) ” I have 50,000 cubic feet of hydrogen per day go- 
ing to waste; will it be profitable for me to install a synthetic 
ammonia plant in order to utilize this otherwise waste 
material ? ” 

Particularly in the earlier period of commercial develop- 
ment of the direct synthetic ammonia process this question 
was very frequently presented. There were a number of 
plants producing oxygen by the electrolysis of water and 
wasting the resultant hydrogen. These plants w’ere all rel- 
atively small, so that while the total of such waste hydrogen 
would have been sufficient for a fair sized synthetic ammonia 
plant, the hydrogen available at any one point was sufficient 
for only from ton to i ton of ammonia per day. The 
figure of 50,000 cubic feet given is perhaps a fair average 

FIXATIOl^ OF atmospheric NITROGEN 


and Is sufficient for ton of ammonia. A plant for the 
production of ton of ammonia would entail very nearly 
as great a capital outlay as would a i-ton plant. It would 
require the same operating labor as for instance a 5-ton 
plant, while the handling and sale of the product would be 
exceedingly expensive, making the whole proposition thor- 
OLiglily impracticable. Hydrogen obtained as a by-product 
of the electrolytic manufacture of caustic soda Is being used 
and to good economic advantage, but not in such small 
quantities. The Roessler and Hasslacher Chemical Com- 
pany Is operating a 3-ton unit at Niagara Falls on waste 
hydrogen. The product Is consumed In other operations 
of the company. This company is also erecting a 6-ton ad- 
dition to its present plant to utilize the by-product hydrogen 
of the Hooker Electrochemical Company formerly em- 
ployed by the Niagara Ammonia Company. The Mathle- 
son Alkali Company Is operating very successfully a 10 to 
1 2 ton unit at Niagara Falls, on by-product hydrogen. The 
smallest plant is a l-ton unit operating on by-product hy- 
drogen at the plant of the Great Western Electrochemical 
Company, Pittsburg, California. This unit, however. Is 
one of the original more or less experimental units of the 
Mathieson Alkali Company. It is believed the capacity of 
this plant will be increased. The Commercial Solvents Cor- 
poration erected a plant at Peoria, Illinois, of a capacity of 
15 tons of ammonia per day, which plant is now operating 
for the production of methanol. The hydrogen is secured 
as a by-product of the fermentation of corn. 

While there might be certain locations of unusual condi- 
tions which might make such a plant feasible, it can be said 
definitely that in general the erection of a synthetic am- 
monia plant merely to utilize 50,000 cubic feet of hy- 



drogen which would otherwise be waste, is commercfally 

(2) ” I nm operating a liquiii air unit for the production 
of oxygen; will it be profitable for me to utilise the waste 
nitrogen for the production of ammonia?” 

This question has undoubtedly been brought up because 
of the name, fixed nitrogen, probably indicating nitrogen as 
the item of cost rather than the fixation. The actual cost 
of the nitrogen is so small a part of the total cost that it 
can have no weight in the decision on the erection of a plant 
unless all other considerations are at least equal. It is 
then of such small importance in the consideration of the 
question that generally speaking it would be wdiolly imprac- 
ticable to erect a plant for the operation of the direct syn- 
thetic ammonia process, in order to utilize otherwise waste 

(3) ” I operate profitably a plant for the fixation 
of atmospheric hitrogen on 10,000 horsepower which I 
have available at very little cost for 12 hours per day, or on 
20,000 horsepower which I have available continuously for 
6 months per year? ” 

The question of off-peak or seasonal powder for use in the 
fixation of atmospheric nitrogen is very frequently dis- 
cussed. Both the arc and direct synthetic amiuonia proc- 
esses must be considered here but the answ'er is the same 
for each. With operation for 12 hours per day or opera- 
tion for 6 months continuously out of each year, a tw’o-ton 
plant would be required to produce an average of one ton 
per day or the investment per annual ton of ammonia would 
be just doubled. If the arc process is considered first and 
power is taken as having a value of $10 per horsepower 
year, which is certainly high for such use, it can be seen that 


the saving through the use of free power figured at this 
rate would be approximately $ioo per ton of nitrogen fixed. 
The plant, however, w'ould cost $1,200 per annual ton of 
nitrogen fixed, which at iS per cent would amount to $216, 
as against $108 for a plant operating continuously. Such 
a plant, in order to utilize free power which could not have 
a value for this purpose even continuously of over $10 per 
horsepower year, would pay $108 for this advantage of a 
maximum of less than $100. In addition, labor costs would 
be doubled or nearly so. This proposition then must be 
considered as being commercially impracticable. 

The same answer presents itself from a consideration of 
the direct synthetic ammonia process. It would not be at 
all practicable to operate this process 12 hours per day. It 
might be possible to produce hydrogen 12 hours and con- 
vert it with nitrogen into ammonia during 24 hour or con- 
tinuous operation. This would necessitate large hydrogen 
storage, however, which would be very nearly if not equally 
as expensive as the additional plant required for 12 hour 
operation. The cost of the plant per annual ton of ni- 
trogen fixed as ammonia would be $520, twice that for a 
plant which would operate continuously; at 18 per cent the 
capital charges would amount to $93.60 per ton rather than 
the regular $46.80, while the advantage from the use of 
free power which might have a full value for this purpose 
of a maximum of $15 per horsepower year would be $35. 
Labor charges would be excessive here too. 

These considerations indicate rather clearly that under 
ordinary conditions at any rate the processes for the fixation 
of atmospheric nitrogen are more or less continuous proc- 
esses and not well adapted to the use of off-peak or seasonal 



(4) “I have a Deico unit on my farm which generates 
8,000 kilowatt hours of electrical energy per dav In excess 
of my requirements; can 1 use tliis for the production of at- 
mospheric nitrogen fertilizers for use on my farni ? 

The answer to the question of using such small power as 
miglit be available from a farm Deico light unit can be 
found in the previous considerations. It is most certainlv 
not economically practicable. The electrical energy cited 
in this case as being available is about enough for the pro- 
duction of Ya ton of ammonia per day, which could be trans- 
formed into 2 tons of sulphate of ammoiua per day for in- 
stance. However, the actual cost of this material, If all 
costs were considered, would be nearly twice that of the 
equivalent material on the market delivered at the same 
site. The investment for the necessary plant would be 
approximately $100,000. The only justification for such 
production, it would seem, would be to provide an 
occupation of interest where cost considerations were of no 

(5) ” Is it economical to utilize the hydrogen of the 
natural gas wells for the fixation of atmospheric nitrogen? ” 

This question is one which has had and indeed is now 
having considerable time and study devoted to it. The 
principal wells now being considered are those of the Ther- 
matomic Carbon Company at Sterllngton, near Monroe, 
Louisiana. This company is cracking the natural gas for 
the removal of carbon as carbon black, thereby releasing to 
the atmosphere millions of cubic feet of gas of an approxi- 
mate composition of 92 — 94 per cent hydrogen and 8 — 6 per 
cent methane with slight other impurities. This it would 
appear is a source of hydrogen for the production of syn- 
thetic ammonia, which is of great value. However, there 



are several drawbacks which have undoubtedly prevented 
industrial interests from using this gas. In the first place, 
the removal of the methane is an unsolved problem indus- 
trially, and secondly, there is no certainty of supply. Any 
or all of the wells of this field might shut off almost over 
night. It might be argued that a water-gas plant could 
then be erected while the advantages of the iiatural hy- 
drogen would have been enjoyed as long as the supply 
lasted. The difficulty there is that a water gas plant would 
naturally be erected at a site near low priced coal and coke, 
wlficli site or sites may not be in close proximity to the gas 
well. Such is the case at Monroe. 

This question is far from settled, however, and this hy- 
drogen may yet be utilized. A report later denied was 
published to the effect that the I. G. Dyestuffs Corporation 
of Germany had secured an option to a lease or purchase of 
the properties at Monroe. It is known that several groups 
of technicians of these German interestSi of which the Ba- 
dische Anilin und Soda Fabrik was foremost, made a vei*y 
detailed study of the situation and it is believed that some 
of the members of the commission reported favorably on 
the project. 

(6) " Is it economically feasible for the city gas com- 
panies to utilize their off-peak gas producing equipment for 
the production of hydrogen for the fixation of atmospheric 
nitrogen as ammonia ? ” 

A pamphlet of the American Gas Association shows .that 
there are large city gas production units which are idle 
about II months of the year in order to take care of the 
peak load of the year, the period from Thanksgiving to 
Christmas. Consideration has been given by this associ- 
ation to the feasibility of utilizing this off-peak equipment 



for tlie production iif liydi'Ogen for, among other materials, 
the production nf synthetic ammunia. 

A study of tlie situation, however, iliscloses tlnit tiie 
equipment available at a city gas works for use in the syn- 
thesis of ammonia represents only lo per cent of the total 
cost of a new plant built from the ground up, A plant 
utilizing this off-peak equipnieiit could then by operating 9a 
per cent of the time just break even w-itfi a complete new 
plant operaring 100 per cent of the time. The advantage 
would be that the investment in this gas equipment would hr 
taken care of during the time it w'ould otherwise be idle. 
However, there are a number of conditions such as unsuit- 
able plant location, perhaps, and certain operational diffi- 
culties from such dual use of equipment which would un- 
doubtedly offset this advantage and render the use of such 
equipment impracticable. Here again there might be cer- 
tain local conditions in a few instances which would reiider 
tliis attractive but generally speaking it can be considered 
as not commercially feasible. 

Chapter VII 


The preceding cliapters indicate tliat from the present 
viewpoint at least the nitrogen source of the future will 
be the direct synthetic ammonia process for the fixation 
of atmospheric nitrogen. Chile nitrate, the arc process 
and the cyanamidc process are all gradually but neverthe- 
less efi’ectively being displaced as sources of supply by the 
synthetic ammonia process. 

Sir Max Muspratt, a director of Imperial Chemical In- 
dustries, Ltd., recently made the statement in London that 
the “ fixation of atmospheric nitrogen through the inter- 
mediate stage of ammonia seems to have established itself 
as definitely superior to other methods of fixation.” He 
advised further that the production of cyanamide is " cer- 
tainly waning,” and that the natural nitrate of soda from 
Chile has the greatest difficulty in competing with fixed ni- 
trogen of synthetic origin. 

In view of this condition, then, it is of the greatest im- 
portance to those interested in the fixation of atmospheric 
nitrogen to consider the conversion products of ammonia, 
the immediate fixed nitrogen product of the direct synthetic 
ammonia process. Although ammonia is used as such in 
refrigeration and the chemical industry, its greatest use at 
this time is undoubtedly as the nitrogen carrier for various 
fertilizer salts. As was mentioned earlier, these salts may 
be formed by the neutralization of various acids with 



i‘i I 

111 Figure VIII are shown diagrammaticall) the Enw 
charts for the materials ammonium sulphate, ure.u nitric 
acid, ammonium nitrate and ammiiiiium phosphate. These 
are the materials of perhaps most immediate concern and 
from which various combinations can be prepared. 

Although sulphate of ammonia is very wididv produced 
at tins time and it is felt in some qua rters that the market 
is supersaturated, it is believed that hucause the sulphate is 
so well known to the fertilizer trade, it will be fiivcii serious 
cansideratioii as a consumer of further increases in syn- 
thetic ammonia production. 

Utilizing sulphuric acid, ammonium sulphate may be pro- 
duced by either the cold or hot method. 

In the first method, usually employed at die by-product 
coke Ovens, the gas containing i to 2 per cent of ammonia 
as it comes from the ovens is partly cooled and passed 
through the tar extractor to the ammonium sulphate satu- 
rator containing dilute sulphuric acid. The resulting salt is 
ejected from the saturator to the drain tables or settling 
boxes, while the gas minus its ammonia passes out through 
an acid trap. 

The saturator in this case is maintained at about 60*^ C 
(3:40^ F). The excess water introduced with the sulphuric 
acid and as wash water is carried off with the large volume 
of gas passing through the saturator. 

In the hot method, which will be discussed here, the am- 
monia is Introduced as practically 100 per cent ammonia 
gas and the saturator maintained at 105*^ C (221“ F). 
The excess water in this case passes off as steam. 

The flow for this operation is shown In the diagram. 
From an acid supply the 60° Be. sulphuric acid flows by 
gravity through a measuring box to the tower distributor. 


Flow Dia):;ram i^or Ammo>iia CiinversioN PiIoduCts 



over tlie checkered packing of the absorptiom tower, and 
into the saturator, 

Amnionia gas brouglit m througii a main enters the sat- 
urator through the ammonia distributor, from whicli it 
bubbles up through tlie liquor wliich absorbs it. Any am- 
mcinia not absorbed passes out into the tower, where it i? 
picked up by the descending acid sprav and returned to the 

By means of the steam ejectors, the resulting crvstal- 
laden liquor is ejected to the trough serving the settling 
boxes. In these boxes the crystals are permitted to build 
up while the liquor drains off to the return trough and is re- 
turned to the saturator. When sufficient crystals have col- 
lected in the settling box, they are raked to the centrifugal 
drier, where they are w'rung free of the larger part of the 
liquor. Final drying takes place in the rotary driers from 
which the sulphate may be removed to storage. 

Because the size of the crystals decreases as the acidity 
of the saturator is increased, it is very important to niaintain 
this acidity at a low concentration. In plants using by- 
product coke-oven gas, the acidity is maintained at about 2.5 
per cent. This is possible because this gas, as prevloiLsIy 
mentioned, is relatively low in ammonia. It would not be 
practicable when utilizing 100 per cent ammonia gas, how- 
ever, to drop this acidity below 4 per cent, the range being 
usually 4 to 7 per cent sulphuric acid. For the present pur- 
pose, the acidity of the saturator will be considered as being 
7 per cent. 

The reaction with heats of formation per mol from the 
elements, for the substance in the state indicated is : 

2 NHg (gas) -h H2SO4 (7%) = (NH4)2S04 (aq.) 

23,780 cal. 209,680 cal. 281,000 cal. 



The heat evolved, therefore, is 47,540 calories per mol of 
sulphate. In addition there is evolved a heat of dilution 
of acid, 77.67 per cent (60° Be.) sulphuric acid to 7 per cent 
of 8,669 calories per mol. The total heat evolved, then, 
is 47,540 -h 8,669 = 56,209 calories per mol of sidphate. 

Let it be considered that all this heat is utilized in con- 

verting water at 20° C to steam at 100° C. Each gram of 
water vaporized will consume 80 -|- 53^*7 (la- tent heat of 
vaporization) or 618.7 calories. 56,209 calories per mol 

of sulphate are equivalent to ~ or 426 calories per 

^ 3 ^ 

i^ram. Then ^ X = 164 gallons of water 
^ 618.7X454 8.4 

may be evaporated per ton of sulphate produced. 

One ton of sulphate of ammonia is the equivalent of 515 
pounds of ammonia and 1,912 pounds of 6o*^ Be. sulphuric 
acid. Allowing for loss of acid, it can be considered that 
one ton of sulphate requires one ton (2,000 pounds) of 60 ° 
Be. sulphuric acid. A ton of this acid contains approxi- 
mately 447 pounds or 53 gallons of water. The difference 
between the 164 gallons of water which may be evaporated 
and the 53 gallons brought in with the acid, or 1 1 1 gallons, 
is the quantity to be admitted to the system as wash water. 

Although this wash water should be hot as used, perhaps 
8 o"^ to 90"^ C, and so enter the saturator at something over 
20 ° C, yet the recirculated water loses some of its heat in 
circulating from the saturator through the troughs, settling 
boxes, and centrifuge back to the saturator and enters the 
saturator at something below loo"^ C, These two diver- 
gences from the assumed conditions can be considered 

as approximately balancing each other, leaving the result 



If it is considered that a centrifuire when loaded contains 
the equivalent of 250 pounds of drv sulphate, then eacli 
wringing of a batch of sulphate may be washed with approxi- 
mately 14 gallons of water. As the centrifuge operator, 
however, need not be skilled, but rather mechanics llv 
trained to this operation, and as the sulphate is not weighed 
into the centrifuge nor the wash water measured, this hjrure 
of 14 gallons serves merely as a guide. Actually, a careful 
check of conditions within the saturator must be main- 
tained. It is very easy to admit too much water, requiring 
additional acid to keep up the acidity, and tlius build up 
the quantity of liquor beyond the capacity of the saturator. 

The quantity of sulphate as centrifuged would build up 
a cake 6 to 8 inches thick round the inner periphery of the 
basket. During loading the centrifuge should be rotated 
so as to build up a cake of uniform thickness. At the 
same time, however, rotation should be slow enough to pre- 
vent excessive lose of sulphate through the holes in the basket 
and also to prevent splashing beyond the confines of the 
centrifuge of the hot liquor. A maximum speed of 150 
r.p.m. has been found satisfactory wTile loading after 
which for drying purposes this speed should be increased 
to 350 r.p.m. and maintained at that speed for approxi- 
mately 5 minutes. 

With an acidity of the saturator of 7 per cent, the result- 
ing sulphate crystals are very small. More rapid rotation 
of the basket than 350 r.p.m. packs the cake so tight as to 
render it difficult to remove. Because of a rotation of only 
350 r.p.m., however, the sulphate discharged from the 
centrifuge contains about 3 per cent of moisture, necessita- 
ting further drying, as by the rotary drier shown in the 
diagram, to less than the allowable limit of 0.5 per cent. 


In both Germany and England, at the synthetic ammonia 
plants of the Badische Anilln and Soda Fabrik and the Syn^ 
tlietic Ammonia and Nitrates, Ltd., respectively, sulphate of 
ammonia is produced from synthetic ammonia through the 
use of gypsum (calcium sulphate), rather than sulphuric 
acid. While there are large deposits of gypsum in Germany, 
there are no important sources of sulphuric acid. 

In this method of production, gypsum is ground to a very 
fine powder and treated while in suspension in water with 
ammonia and carbon dioxide in a closed vessel for 6 to 9 
hours. The reaction is expressed by the equation 

CaS04 H2O -b 2 NH3 -h CO2 = CaCOs -h (NHO2SO. 

Both calcium carbonate and ammonium sulphate are formed. 
The precipitate of calcium carbonate is filtered off and the 
solution of ammonium sulphate evaporated to obtain the 
solid salt. In the Merseburg plant in Germany, 2,300 tons 
of gypsum were being consumed daily in this operation in 
1923, for the production of 2,000 tons daily of sulphate of 
ammonia. The gypsum is obtained from the company’s 
own mines in the Harz Mountains, abort 60 miles south- 
east of the plant. 

The disposal of the calcium carbonate sludge is some- 
what of a question. It is for the most part run out onto 
the ground, forming large puddles or lakes. Some small 
quantity of it has been disposed of as a chalk or lime for 
soil conditioning and an attempt is now being made by the 
English company to reduce the hygroscopicity of ammonium 
nitrate by mixing the two in such a proportion, nearly ton 
for ton, that the resulting material will contain 15.6 per 
cent nitrogen, as does Chile nitrate. It is understood that 
the Badisbche company experimented with this some years 
ago and found it to be rather unsuccessful. 



The gypsum method of sulpliate of ammonia production 
is ratlicr well adapted to tliat form of the synthetic ammo- 
nia process which utilizes hydrogen from water gas, as the 
necessary carbon dioxide is a waste gas in the production of 
hydrogen from water gas. 

It is the availability of carbon dioxide in such ammonia 
production that makes the synthesis of urea attractive. 
The general flow for this formation is shown in the dia- 

Ill practice, ammonia and carbon dioxide either separately 
or a mixture are compressed to about too atmospheres 
and admitted to an autoclave. The mixture of these gases 
forms aiiimoiiiuiii carbamate, a very corrosive inateriah 
which is the reason for admitting the gases under pressure 
separately to the autoclave for mixing. The autoclave, 
which may be lead lined, is maintained at about 150' C for 
two hours, after which a mixture of ammonium carbonate, 
ammonium carbamate, urea and water is discharged. This 
autoclave operation may be more or less continuous with 
the compressed ammonia and carbon dioxide entering at 
the bottom and the resulting materials discharged at the 
top. This mixture is then treated in a still at about So" C, 
where the ammonium carbonate and carbamate are broken, 
down to gaseous ammonia and carbon dioxide- These 
gases are then separated in a column and returned sepa- 
rately for recompression and treatment- The solution of 
urea is discharged and the water evaporated from it, leav- 
ing the solid. 

Urea is the most highly concentrated of the nitrogen 
solids, containing about 46 per cent nitrogen. Because of 
this high concentration. It is very well suited for small gar- 
den plot fertilization, and is generally applied in solution, 
a teaspoonful in a gallon of water. It has not, however. 


proven very attractive to the fertilizer trade, although at- 
tempts were made through cost concessions to introduce it. 

There are two general forms of nitrogen in the fertilizer 
trade, ammonia nitrogen and nitrate nitrogen. Although 
it was once considered necessary to supply the bulk of the 
nitrogen in the nitrate form, this idea .has gradually changed 
with the increased supply of ammonia nitrogen, until it is 
conceded that the proper balance may he maintained with 
at least 6o per cent of the nitrogen in the ammonia form. 
The remaining 40 per cent, however, must be a nitrate ni- 
trogen, which, if the nitrogen is fixed as ammonia, must be 
a conversion product of the ammonia. 

The flow for the oxidation of ammonia to form intric 
acid is shown in the diagram. The process consists in pass- 
ing a mixture of air and 10 per cent of ammonia through a 
catalyst at a temperature of about 800° C, resulting in the 
formation of nitric oxide and water essentially as shown by 
the equation 

4 NH3 -h 5 02= 4 NO -h 6 H2O. 

As in the arc process, the nitric oxide thus formed is oxi- 
dized and absorbed in water, producing nitric acid of 50 per 
cent HNO3 strength, according to the reactions 

2 NO -h O2 = 2 NO2 

3 NO2 -h H2O = 2 HNOs -h NO 

The catalyst in general use to effect the oxidation of am- 
monia is platinum drawn to fine wire and woven into a fine- 
mesh gauze. Theoretically there is very little loss of plati- 
num, so that the gauze is simply a capital charge in the cost 
of the nitric acid. Actually, however, there is a mechanical 
loss of platinum which must be considered in the cost of the 
nitric acid. The platinum should be free from iron and all 




Other impurities except that a small amount of iridium, per- 
haps less than i per cent, is not harmful. The gauze is often 
woven with an iridium wire selvage edge to add strength. 
The gauze used in the oxidizers at the U. S. Nitrate Plants 
was of So mesh, woven of 0.003 wire. 

There are two types of oxidizers, that requiring a flat 
rectangular gauze, and that requiring a circular gauze. 
The flat gauze is heated electrically to the reaction tem- 
perature, 700° C to 1000° C, while the circular type needs 
no heating or even preheating of the gases. The heat of 
oxidation maintains the gauze at proper temperature. The 
electrically heated catalyzer, however, has good tempera- 
ture control, which enables it to work successfully on im- 
pure ammonia gas. The flat type is held along all four 
edges, while the circular type is held along only two selvage 
edges, which are then inactive. In the United States, flat 
gauzes 13 inches by 27 inches with an exposed area of 12 
inches by 24 inches and circular gauzes of 13 inches by 114 
inches, rolled in a cylinder of 4 thicknesses of gauze, each 
w’ith an exposed area 1 1.5 inches by 9 inches in diameter, or 
a surface area of 11.5 inches by 28.3 inches, have been used. 
At the higher temperatures, the platinum has much greater 
capacity for oxidizing ammonia than at lower tempera- 
tures and is much less affected by catalytic poisons. 

Base metal catalysts have been used but not with the 
success achieved with platinum. Further work is now be- 
ing done at various places on base metal catalysts and ex- 
cellent progress is being made in this direction. Attempts 
are also being made to carry out the reaction with oxygen 
rather than air in order to facilitate absorption of the ni- 
trogen oxides formed or to enable the product to be ob- 
tained in the form of liquid nitrogen tetr oxide. This liquid 



has been studied with a view ta its utilization in the direct 
nitration of organic compounds, and in the production of ni- 
trogenous fertilizers by absorption in various carriers. 

The development of high cliromium steel alloys for use in 
tower and tubing construction for the absorption svstein 
has made possible economies in the operation of ammonia 
oxidation. Instead of tlie former massive brick towers, 
smaller circular towers of this 17 per cent chromium steel 
are now used. 

The hot gases coming from the oxidizers are cooled in 
the gas cooler constructed of chromium steel ami then pass 
to die oxidation and absorption towers. The number and 
size of tile towers varies witli local conditions and the capac- 
ity of the plant. These towers are usually operated under 
atmospheric pressure and are packed with spiral tower pack- 
ing rings. The gas passing through these tow'ers in series 
passes couhtercLirrent to the supplied w’ater, which is added 
at the end of the system, so that the strongest acid meets the 
most concentrated gases and the weakest gases are scrubbed 
with nearly pure water. 

The 50 per cent acid obtained may be concentrated 
through the use of strong sulphuric acid. A tower similar 
to the absorption tower is supplied with strong sulphuric 
acid and the weak nitric acid W’hich trickles down over 
the tower packing and is treated with steam introduced at the 
base of the tower passing counter current to tlie flow of the 
acid mixture. The distilled concentrated nitric acid is drawn 
off near the top of the tower and condensed In the condenser 
tubes, while the sulphuric add is drawn off at the bottom, 
concentrated and used over again. 

Parsons ’ gives a cost comparison of nitric acid from 

^ Ind. Cheni. jp, 789 (i9i7). 



amrnonia oxidatioii aud from Chile nitrate, as follows; 

I, Fvovi Ammonia'. 

As NO gas 

xAs 50 per cent HNO3 
As 95 per Cent HNOj 

Per Ton HNO3 (100 per cent) 
$3.00 cost of 564 lb, NHij 
10.60 -j- cost of 581 Ib. NHjj 
2J.60 -)- CDSl of 606 lb. NHg 

II. From Chiieem Fiitrate: 

As 95 per cent HNO^ $32.00 -|- cost of 2840 Ib. N„NOg 

If the cost of ammonia is considered as being as high as 
6 cents per pound and Chile nitrate taken at the present 
quotation of $2.25 per 100 pounds, tfie cost of 95 pev cent 
nitric acid as worked out from this table is $59.96 per ton 
through ammonia oxidation and $63.90 through Chile 

In the production of ammonium nitrate through the neu- 
tralization process as shown in the diagram, ammonia gas 
is passed into nitric acid and the solution evaporated until 
practically all of the water has been eliminated. The re- 
action involved is essentially as expressed by the equation 

HNOs -b NH3 = NH^NOs. 

Ammonia gas and nitric acid are continuously fed into 
the inclosed neutralizing tank, the feed being so regular 
that a practically neutral solution is obtained. This solu- 
tion; overSoT^-’s into a tank where it is adjusted to neutrality. 
The temperature in the neutralizer rises to about 100° C, 
due to the heat of neutralization. The steam thus gener- 
atedj together with unabsorbed ammonia, passes out through 
the top of the neutralizer into a cooler io which the moist- 
ure is condensed and drains back into the neutralizer. The 
unabsorbed ammonia Is recovered in an absorbing tower in 
which it is scrubbed out with acid. The solution adjusted 
to neutrality is evaporated until it contains less than 3 per 



cent of water, and is tlieii crystaliized in jacketed grainers 
by continuous stirring for several hours while its tempera- 
ture is properly controlled by admitting steam or cold water 
to the jacket. The grained product is discharged from 
the grainer after it reaches a temperature of about 70“ C. 

Although ammonium nitrate gives excellent results as a 
fertilizer, it unfortunately is extremely hygroscopic, which 
renders it very difficult to handle. Because it is a concen- 
trated material containing 35 per cent of nitrogen and is 
such a good fertilizer material, much work has been done 
on the development of a treatment to counteract its hygro- 
scopic nature. Inasmuch as means such as graining and 
mixing with other salts have been developed for reducing 
this hygroscopicity, and since it is a nitrate form of nitrogen, 
it is believed it will be given serious consideration for use 
in this country. 

Ammonium phosphate, because it is a concentrated ma- 
terial containing two plant foods, is sure to become an im- 
portant fertilizer salt in this country. It is already occupy- 
ing attention in Europe and is being produced in Germany. 
The American Cyanamid Company has been producing it 
in this country under the trade name of " Ammo-Phos,” one 
grade of which is a mixture of ammonium sulphate and phos- 
phate obtained by neutralizing a mixture of phosphoric and 
sulphuric adds with ammonia. It is produced in two grades, 
One of 14 per cent ammonia and 47 per cent PzOfo and the 
other 20 per cent ammonia and 20 per cent P-O- The reg- 
ular mono-ammoiiium phosphate contains 14.7 per cent am- 
monia and 61.7 per cent P2O:;. 

” Ammo-Phos ” because of its high cost, being produced 
with ammonia from cyanamlde, has not been able to find a 
market in this country but has been exported chiefly to 


1 14 

the Orient, The longer the freiglit haul, the greater is the 
possibility of sale as one ton of the 14 "47 grade is the 
equivalent of approximately 3)^ tons of the necessary am- 
monium sulphate and acid phospiiate to supply the same 
plant food. The freight on 2).^ tons of material may then 
be used to offset any manufacturing cost differential. 

The flow for the manufacture of ammonium phosphate 
as shown in the diagram is the same as for the sulphate. In 
fact, the identical plant could be used, providing concen- 
trated phosphoric acid were available. If weak acid such 
as results from the wet method of treating phosphate rock 
with sulphuric add is employed there is no use for the centri- 
fuges. The liquor as it comes from the saturator is led into 
tanks where it is adjusted to neutrality. This liquor al- 
though very thin is then led into the rotary drier from which 
the conrained water is evaporated, resulting in the salt, 
phosphate of ammonia. Triple effect evaporators have 
been tried in the system immediately before the driers, but 
in evaporating it is difficult to maintain the solution neutral 
and the acid material quickly eats out the interior of the 
evaporator. In the rotary drier a protecting cake of phos- 
phate is built up on the walls. 

The advantage of ammonium phosphate over the sul- 
phate salt for instance is in the fact that the acid ammonia 
carrier is in itself a plant food. 

The foregoing are the principal immediate conversion 
products of ammonia. There are^ however, a large num- 
ber of combinations of nitrogen materials now being worked 
up for fertilizer use. The physical properties of most of 
the fixed nitrogen products which contain nitrogen as the 
only fertilizer ingredient are far from satisfactory in that 
they readily absorb moisture from the air, and cake or pos- 


sess other properties which greatly interfere with their use 
as fertilizer. Considerable attention is being given to medi- 
ods for improving the mechanical condition of these ma- 
terials, This might be done by granulation, by coating 
with insoluble materials, or by the formation of two constit- 
uent fertilizer salts such as the ammonium phosphate just 
mentioned and potassium nitrate. These substances are 
among the least hygroscopic of soluble materials and mix- 
tures with each other or with potassium phosphate will give 
a complete concentrated fertilizer. 

In addition to the salts ammonium sulphate, ammonium 
phosphate, ” Ammo-Phos,” and urea previously mentioned^ 
there are other fertilizer materials containing fixed atmos- 
pheric nitrogen now 011 the market. The principal ones of 
these are: 

Leuna-salpeter, a double salt of ammonium nitrate and 
ammonium sulphate containing nitrogen equivalent to 31. 5 
per cent ammonia. About one-fourth of the nitrogen is 
nitrate and the remainder is ammonia nitrogen. It is 
mixed approximately 1,245 pounds of sulphate and 755 
pounds of the nitrate per 2,000 pound ton. This material 
is produced by the Badische company at the Leuna-Werke 
in Germany from which the name is derived. 

Nitrate of lime or calcium nitrate is a compound of lime 
and nitric acid so treated, for instance by atomizing with air, 
as to give a material suitable for broadcasting. It contains 
15,5 per cent nitrogen and 28 per cent lime. 

Potassium-ammonium nitrate Is a mixture of potassium 
and ammonium nitrate containing 15.5 per cent nitrogen, 
half as ammonia and half as nitrate nitrogen, and 27 per 
cent potash. This is a very fine fertilizer material of good 
physical properties. 


Diammonium phosphate, exploited iii Germany, is an- 
other ammonium phosphate containing twice the ammonia 
of the monoammonium phosphate and is produced by treat- 
ing monoammonium phosphate liquor with additional 
ammonia. This material contains 23 per cent of ammonia 
and 47 per cent of phosphoric acid. 

Leuiiaphos is also a product of the Leuna plant. It is a 
compound of diammouium phosphate (diammonphos) and 
ammonium sulphate containing 24 per cent of ammonia and 
15 per cent P2O5 (phosphoric acid). 

Leunaphoska, another material of this plant, is a mixture 
of leuiiaphos and potash salt which contains 13 per cent ni- 
trogen, equivalent to 15.7 per cent ammonia, 10 per cent of 
phosphoric acid and 13 per cent of potash. 

IMaiiy other materials comprising mixtures of ammonia, 
phosphoric acid and potash are being worked on but all of 
the above are being commercially exploited. 

Chapter VIII 

The world’s demand for inorganic iiitrogeu Is increasing at 
the rate of about 100,000 tons of fixed nitrogen per year 
and according to the reports of several individuals thor- 
oughly conversant with the situation, of whom Sir Max 
Muspratt, previously mentioned, is one, there is no expecta- 
tion of any lower rate of increase in sight. 

The world figures for the three years ending June 30, 
1925, 1926 and 1927 are given below. 

Tons of Nitrogen for year ending 

June 30 

June 30 

June 30 




Chile nitrate 




By-product ammonia 
Fixed atmospheric 



341 ,000 









From these figures it can be seen that fixed atmospheric 
nitrogen not only supplied the increased demand of 100,000 
tons of nitrogen per year, but it has also made up 
the difference due to the falling off of Chile nitrate. This 
decrease in Chile nitrate amounted to over 50,000 tons of 
nitrogen per year for the past three years so that the in- 
crease in fixed atmospheric nitrogen has been approximately 



150,000 tons of nitrogen per year. Even with this large 
yearly expansion, it Is believed that the saturation point in 
consumption of nitrogen is not yet in sight and that there is 
room for all producers now engaged in the industry. Col. 
Pollitt, of Nitram, Ltd,, of England, has pointed out in a 
recent speech in Edinburgh, that for at least 500,000 years 
a hunian being very little different from his present form 
has inhabited the earth. In all that time up to A.D. iSoo, 
the world’s population had increased from its beginning to 
a figure estimated at 800 millions. In the next 100 years 
from A.D, 1800 to A.D. 1900, it rose to 1,730 millions, or 
more than doubled, and this rate of increase or one very 
nearly as great, is continuing today. This increase obvi- 
ously cannot be continued indefinitely under any circum- 
stances, and it cannot go on at all unless the productivity of 
the soil keeps pace with it. 

For the year ending June 30, 1927, Chile supplied 20 per 
cent of the world’s inorganic nitrogen consumption, the by- 
product coke ovens supplied 24 per cent, while atmospheric 
nitrogen fixation processes supplied 56 per cent. This is in 
contrast to the situation 30 years ago, the time of the warn- 
ing sounded by Sir William Crookes, when the world was 
very nearly 100 per cent dependent upon Chile. 

Of the 807,000 tons of nitrogen represented by the 56 per 
cent from tfie atmosphere, only 39,000 tons or less than 5 per 
cent was fixed by the arc process, 175,000 tons or less than 
22 per cent was fixed according to the cyanamide process, 
while 593)000 or over 73 per cent was fixed according to the 
direct synthetic ammonia process. A comparison of these 
figures with those for the previous year leaves no doubt of 
the trend of development. Of the 641,000 tons produced 
during the year ending June 30, 1926, the arc process ac- 


I ig 

counted for 41,000 tons or 6Jd per cent, the cyanamide proc- 
ess produced 185,000 tons or 29 per cent, while 415,000 
tons or 64 per cent was produced by the direct synthetic 
ammonia process. Not only did tlie increase of 178,000 
tons in the year in direct synthetic ammonia process capacity 
account for the total increase in fixed atmospheric nitrogen 
production, but it also accounted for the decrease hi produc- 
tion by the arc and cyanamide processes. Thus, the breach 
is growing larger from botli ends, the decrease in produc- 
tion of the two earlier processes and the increase in produc- 
tion of the newest process, the direct synthetic ammonia 

Fixed atmospheric nitrogen and more especially the direct 
synthetic ammonia process is fast approaching the position 
once enjoyed by Chile nitrate, but it can never from present 
indications actually achieve that position. Ammonia it is 
believed will always be produced as a by-product of the 
operation of the coke ovens. The production of by-prod- 
uct ammonia will increase, but it is believed its increase w’ill 
be very slow. 

All statistics point clearly to the fact that the important 
source of fixed atmospheric nitrogen of the future, as it is 
of the present, will be the direct synthetic ammonia process. 
The maximum annual capacity of all the plants now operat- 
ing is 720,660 tons of nitrogen per year, while there is under 
actual construction additional capacity of 225,345 tons of 
nitrogen, or nearly 1,000,000 tons capacity operating and 
under construction. 

Germany, of all the countries of the world, is by far the 
largest producer and during the year 1926-1927 her pro- 
duction exceeded consumption of Chile nitrate even for 
1917, the year of greatest consumption. Of 593 )^ 0 ^ tons 



of nitrogen fixed in the world for the past year, the plants 
of Germany fixed 440,000 tons, divided Into 125,000 tons 
fixed at the Oppau plant and 315,000 tons at the Leuna- 
Werke at Merseburg. In addition to this, the cyanamide 
Interests of Germany are erecting a direct synthetic am- 
monia plant of the Fauser naethod at their cyanamide plant 
in Piesterltz, which it is expected will be brought into 
operation shortly. 

The closest competition with Germany at this time, if in- 
deed she can be considered as having competition, is from 
England. That country, through the Synthetic Ammonia 
and Nitrates, Ltd., a subsidiary of the Brunner-Moiid and 
Imperial Chemicals, Ltd., now operating a direct synthetic 
ammonia plant at a capacity of 22,000 tons of nitrogen per 
year for fertilizer materials and actively erecting an addi- 
tion of 53,000 tons of nitrogen per year, is planning on fur- 
ther increasing capacity by addition of a 75iOOO ton unit, 
bringing the total capacity of the plant to 1 50,000 tons of ni- 
trogen per year. It is expected that the 53,000 ton addi- 
tion will be in operation by the first of the year 1928. Hy- 
drogen, here as in the case of the German plants. Is secured 
from water gas. 

In the United States the combined total capacity of the 
seven operating direct synthetic ammonia plants is 28,500 
tons of nitrogen per year, equivalent to 99 tons of ammonia 
per day, while the capacity operating is only 23,000 tons of 
nitrogen per year, equivalent to 80 tons of ammonia per 
day. All of this production has gone Into the refrigeration 
and chemical Industi^y, but it has practically completely sup- 
plied that demand, having replaced ammonia from the gas 
works and coke ovens. 

The plants operating in this country, with their -capacities 















Lnit )'j] 

Atmospheric Nitrogen 



N. Y. 

40 1 


It, 550 

La20te, Inc. 


(Dupont subsidiary) 

W. Va. 



Mathieson Alkali Works 

Niagara Falks, 


N. Y. 



2, goo 

Niagara Ammonia Co. 

Niagara Falls, 

(Dnpont subsidiary) 

N. Y. 

' 17 




Niagara Falls, 

Chem. Co. 

N. Y. 




Pacific Nitrogen Corp, 

(Dupont subsidiary) ' 

Seattle, Wash, 




Great Western Electro- 


chemical Co 





Commercial Solvents 


Peoria, 111 . 








Of this capacity of 1 14 tons of ammonia daily, 65 tons or 
57 per cent is for operation On water-gas hydrogen, 37 tons 
or 32 per cent is for operation on hydrogen, a by-product of 
other chemical industries, while only 12 tons or less than ii 
per cent is for operation on electrolytic hydrogen. Of the 
operating rate of 80 tons per day, only 3.7 per cent is On 
hydrogen from the electrolysis of water, while 70 per cent 
is on water-gas hydrogen and over 26 per cent on by-product 

The difference of 34 tons between the rated daily capacity 
of 1 14 tons and the daily operating capacity of So tons ts 
caused by Lazote diverting 10 tons ammonia capacity to the 
production of methanol; by the fact that 9 tons capacity of 
the Niagara Ammonia Company is idle due to the fact that 


FDLmoN OF atmospheric nitrogen 

it is not economically practicable in the United States to use 
electrical energy as a substitute for coal in the fixation of 
atmospheric nitrogen (the 8 ton capacity operating utilizes 
hydrogen a by-product of the Hooker Electrochemical Com- 
pany chlorine plant) ■ and by the Commercial Solvents Cor- 
poration converting its 15 ton ammonia unit to the produc- 
tion of 4,000 gallons of methanol per day. 

The Atmospheric Nitrogen Corporation, now operating 
the largest direct synthetic ammonia plant in the United 
States, is preparing for the erection of a large plant for this 
process for the production of fertilizer materials at Hope- 
well, Virginia. Indeed it is reported that construction has 
already started on the Hopewell site and that much of the 
equipment has been ordered and the fabrication of some 
completed. This plant will mark the entrance of the direct 
synthetic ammonia process for fertilizer production in this 
country and it is expected that expansion will be rapid. 

The plant of Lazote, Inc., operating at Charleston, W. 
Va., is somey/hat novel, in that the purification step of re- 
moving carbon monoxide from the water gas is accom- 
plished by converting it with hydrogen into methanol. Thus 
the two synthesis processes ave linked together and the puri- 
fication step which used to be a costly one is turned to a 
profitable one. It is reported that large expansion of this 
plant in the near future is planned* In fact, it has been 
said that the plant will eventually, within the next few years, 
be enlarged to a capacity of 300 tons of ammonia per day. 
It is believed that this company is carrying on extensive re- 
search looking to the development of new uses for ammonia. 

The plant of the Mathieson Alkali Company is operating 
on hydrogen which is a by-product from their caustic manu- 
facture, It is not believed that there will be much if any 



expansion in this project, but because of the favorable situa- 
tion as regards hydrogen costs this company will always be 
able to produce. 

The Niagara Ammonia Company, operating the Casale 
process and lately acquired by the Dupont interests, was 
erected for operation of about half capacity on hydrogen 
obtained by the electrolysis of water and half on hydrogen 
as a by-product of caustic manufacture of the Hooker Elec- 
trochemical Company’s plant next door. With the cut in 
price of ammonia, however, the electrolytic plant had to be 
shut down, as hydrogen produced through the electrolysis 
of water, even with the rather favorable power rate pre- 
vailing on the older contracts at Niagara Falls, was too 
costly. The remaining part of the plant using by-product 
hydrogen has maintained operation. 

The Roessler and Hasslacher Chemical Company, oper- 
ating a 3 ton per day ammonia plant on hydrogen, a by- 
product of its own operations, is enlarging its plant. The 
ammonia produced at this plant is used in its owm operations. 

The Pacific Nitrogen Corporation plant at Seattle, Wash- 
ington, is the only plant in the country now operating on 
hydrogen from the electrolysis of water. Although the 
power rate of $30 per kilowatt year is not particularly at- 
tractive for this operation, production is continued economi- 
cally because of other sectional conditions. 

The Great Western Electrochemical Company is oper- 
ating a one-ton unit which had formerly operated as some- 
what of an experimental unit at the plant of the Mathieson 
Alkali Company at Niagara Falls, N. Y. The hydrogen is 
a by-product of caustic manufacture. It is reported that 
this plant is to be enlarged by the addition of two more one- 
ton units. 



The Commercial Solvents Corporation, operating corn 
fermentation plants at Terre Haute, Indiana, and Peoria, 
Illinois, for the production of butyl alcohol (butanol) has 
been wasting to the atmosphere from this operation about 

2.500.000 cubic feet of hydrogen daily* In the interest of 
utilizing this valuable gas, a plant of a rated capacity of 15 
tons of ammonia per day was erected at Peoria, Illinois. 
After operating this plant for the production of ammonia 
for a few weeks, the few necessary changes were made to 
operate it for the production of methanol according to a 
process which permits of the use of hydrogen with carbon 
dioxide, another waste gas of the fermentation process, 
rather than with the carbon monoxide ordinarily employed. 
In view of the fact that it can be readily changed over for 
the production of ammonia again, this plant can be consid- 
ered as potential capacity. Whether the product of the 
plant will be methanol or ammonia at any time will undoubt- 
edly depend on the market conditions. 

The development of the industry in France is largely ac- 
cording to methods which will permit of the utilization of 
coke oven gas. Although the capacity is made up of rather 
a large number of plants, their combined capacity upon the 
completion of present construction will be about 125,000 
tons of nitrogen per year, equivalent to 1 53,000 tons of am- 
monia. There is one relatively large plant included in this 
group, that of the French Government, at Toulouse, which is 
to have a capacity of 5 7,000 tons of nitrogen per year. Wa- 
ter gas is to be the source of hydrogen. Of the remaining 

68.000 tons capacity, 63,000 tons are to operate on hy- 
drogen from by-product coke oven gas. It will be noted 
that in the countries of greatest actual and contemplated 
development, Germany, England, France and the United 



States, coal Is depended upon as the means of hydrogen 

Although not a large consumer, Italy has been increasing 
steadily in nitrogen consumption at a rate of from 15 to 25 
per cent each year for the last 5 years. Domestic produc- 
tion has kept pace with this Increased consumption, so that 
through these years, although imports increased, the do- 
mestic production for each year amounted to about half the 

This increase in domestic production has been through 
the direct synthetic ammonia process. As Italy has practi- 
cally no coal, but has many excellent water-power resources, 
hydrogen for these new operations is all being derived from 
the electrolysis of water. 

Japan like Italy does not possess extensive coal deposits, 
but has large water-power resources, which lend themselves 
to low cost development. In freeing herself of dependency 
on importation of sulphate of ammonia, Japan is utilizing 
these power resources for the production of electrolytic hy- 
drogen for the fixation of atmospheric nitrogen according 
to the direct synthetic ammonia process. In making this 
development, the cyanamide plants are closing down to 
make room for this process of lower production costs. 

In Norway, the Norsk Hydro Company is replacing its 
arc process capacity by direct synthetic ammonia capacity, 
utilizing electrolytic hydrogen. By so doing, this company 
can utilize the same power now being consumed in the fixa- 
tion of 35,000 tons of nitrogen annually to fix 140,000 tons. 
The first unit of this replacement is being installed by an 
American company, the Nitrogen Engineering Corporation 
of New York. 

Sweden is replacing its cyanamide capacity with direct 


synthetic ammonia capacity and this latter process is also 
operating in three plants in Spain and in Belgium to a capac- 
ity of 55.000 tons of nitrogen per year, while plants are 
projected or actually building in Poland, Czechoslovakia, 
Russia, Yugoslavia, Brazil and Australia. 

It can be seen that world development is following the 
direct synthetic ammonia process and that this process is 
rapidly replacing the two older and more costly processes, 
the arc and cyanamide. It will shortly come about that to 
speak of the capacity or of the production by the direct syn- 
thetic ammonia process will be tantamount to speaking of 
fiyied atmospheric nitrogen capacity or production. 


The cost of Chile nitrate, as given by Hobsbawn in the maga- 
zine, Chile, VoL I, No. 5, p. 205, as one of the better ofhclnas. Is as 


Per long ton 
of -filtrate 

(A) Manufacture of nitrate $11.61 

(1) Mining raw material ^3-57 

(a) Wages $3.00 

(b) Explosives 0.42 

(c) Stores 0.15 

(2) Transport of raw material 2.41 

By carts 

(a) Wages 0.76 

(b) Fodder 0.85 

(c) Stores 0.24 

By rail 

(a) Wages 0.28 

(b) Fuel stores 0.28 

(3) Elaboration of raw material 

Crushing, elevating & conveying 5.63 

(a) Wages 0.192 

(b) Power O-075 

(c) Stores 0.050 


(a) Wages I-I30 

(b) Power 1. 140 

(c) Repairs 0.280 

(d) Fuel 2.230 

(e) Stores 0.298 

(f) Water 0.107 

(g) General manageineat 1-125 



Per long ton 
9^% Tulirote 

(B) Baggage and lading 1.86 

(C) Railway freight to port 2,70 

(D) Export duties 12.50 

(E) Shipping charges 1.06 

(F) Commission 0.44 

(G) Capital charges (investment, per annual ton 

of nitrate- producing capacity) 7.6c 

Amorti2ation at 5 per cent 2.00 

Interest, taxes, insurance, etc. 9% 3.60 

Repairs, additions, renewals, etc., 5% .... 2.00 

Total, f.a.s, Chile ^37-57 

If the ocean freight charge is $7.50 per ton, the cost f.a.s. port 
of consuming country is $45. It is often necessary to rebag the 
material at tlie port of entry. This cost must, of course^ be added 
to the f.a.s. port of entry cost. 




rQ2J Ral£ of 
Product) on 


Piesteritz ' 










Bellegarde * 

















The locations of the world’s planis for the fixation of atmos- 
pheric nitrogen by the various processes are as follows; 

Nitrogen Fixation by Arc Process 


Rjukan , Norway 

Notodden, Norway, 

Net Tons 
31,000 ’ 


Net Tons 

Rhina, Germany 



La Roche de Rame, France 



Patsch, Austria 





Nitrogen Fixation by Cyanamide Process 



Nitrogen Fixation by Cyan amide Process — Continued 

LiOCatio 11 

Annual rgzy Rate of 
Capacitf Production 



Domodossola , 
Ascoli Piceuo . 
San Marcel . . 





1 ,000 





United States: 
Muscle Shoals, Ala. 


2 c ,000 



y,ooo I 

7,000 / 





1 5 ,000 






Total 3151500 




Elect loly tic Hydrogen 

SeattlC) Wash., U.S.A. 

Pacific Nitrogen Corp. 


Soulom, France 

Ste. des Engrais Azotes t-i 



Terni, Italy 

Socle ta Ita liana Rlceidie 

Industriali Siri 

i.\ 4 S 

Nera Montoro, Italy 

Terni Societa per I’lndustria 

& I’Eleciricita 

9 ’ 7^5 

Dalinaaia, Italy 

Societa Italians Forse 

Idrauliclic della Dalmazia 


Novara, Italy 

Socieca Piemontesse 

Ammonia (Montecatini) 

S, 75 o 


Merano, Italy 

1 Montecatini 


Mas (Belluno)) Italy 



Sabinandigo, Spain 

Energia Indiistrias Aragon- 

esas, S,A. 

4 > 72 S 

Nobiojka, Japan ; 

Nippon Clil’sso Hiryo 

Kabnshiki Kaisha 


Minamata, Japan 

Nippon Chisso Hiryo 

Kabushiki Kaisha 



Viege, Switzerland 

Usines Electliques de 

la Lonza 



Ljunga, Sweden 

Stockholm Supeifbsfat Akt. 







Nitrogen Fixation by Direct Synthetic Ammonia Process 

Net Tons Nitiogcn per Year 

^ 9-7 







Watei^gas Hydrogen 

Syracuse, K.Y., XJ*S.A, 
Hopewell, Va., U.S.A. 

Atmospheric Nitrogen Corp. 
Atmospheric Nitiogen Corp. 

7 > 75 o 


Charleston) W.V^a., U.S.A. 
Oppai), Germany 

La’iote, Inc. 

Bad is die Anilin und Soda 


Badische Anilin und Soda 


Merseburg, Germany 


Synthetic Ammonia & 

37 S,ooo 

Billingham, England 

Nitrates, Ltd. 
Societe Chimique de la 


j 2,000 

Montercau, Fiance 

Grande Paruisse 



Toulouse, Fiance 

French Government 


Willebrock, Belgium 

Societe Eveocc Coppe 


Hiroshima, Japan 

Suzuki & Company 


Ninjinoiigorod, Russia 

Severny Cliimicecky Trust 






Nitrogen Fixation by Direct Synthetic Ammonia Process 




Coke-oven Hydrogen 

rp27 cgzp Capac- 
Operating ity under 
Capacity Construction 

Bethiine, France 

St, Rtierine, France 
Deca2eville, France 

Henin Lietard, France 
Pont a Vendin, F ranee 
Plenin Lietard, France 

Analn, France 

Calling, France 

Firminy, Fiance 

Vado, Italy 
Ougree, Belgium 
Ostend, Belgium 

Fjdguera, Spain 
Knurow, Poland 

Ignat2, C2echoslovakia 

Maries, France 
ScHaete, Belgium 
Wa2iers, France 

Syracuse, N, Y, 
Niagara Falls, N, Y, 
Niagara Falls, N. Y. 
Niagara Fallsi N. Y. 

Pittsburg, Calif. 
Piestcrit2, Germany 

Widnes, England 
St. Auben, France 

Buss it Italy 
Flix, Spain 

Compagnie des Mines dc 

Houillcres de St. Etienne 
Socle te de Commentry Four- 
chanbault et Decaxeville 
Ste. des Mines de Dourges 
Ste. des Mines de Lens 
Cie des Mines dc Vicoigiie 
Noeux & Drocoi/n 
Clc des Produits Chimiques 
An2in Kuhlmann 
Ste. Honlllere de Soi re et 

Cie des Produits Chimiques 
de Roche La Moliere 
Societa Azogeno 
Societe Beige de F Azote 
S.A. des Fours a Coke 
Semet Solvay and Plettc 
Societe Ibcrica del Nitrogen 
Societe Fermicre dcs Mines 
Fiscales de PEtat Polonais 
Societe Czechoslovakia 

Societe des Mines de Maries 
Etabilissements Kuhlmann 
Soc. FAmmoniazue Synthc- 


By-plod uct Hydrogen 

Atmospheric Nitlogen Corp. 
Niagara Ammonia Co. 
Mathieson Alkapli Works 
Roesslei-Hasslacher Chem. 

Gr, Western Electrochemical 
Mitteldeutsch Stickstoff 

United Alkali Co., Ltd. 

Cie d’ Ala is Froges et 
Societa Azogeno 
Societe Iberica del Nitrogeno 



































Grand Total 

721,9 lo 


Some nitrogen statistics of domestic production, exports, im 
Great Britain, France, Italy and Japan tor various years from 

(Expressed in net 






Domestic Productiun: 

By-product ^immonia 





Fixed atmospheric nitlogen 



1 6^980 


Total production - . . 

90, 167 


31 1,180 



Chilean nitrate 

4,1 12 




By-produet ammonia 





Fixed atmospherie nitrogen 





Total exports 






Chilean nitrate 




1 3 j6o2 

By-product ammonia 

6, go I 




Fixed atmospheric nitrogen 





Total impoits 






Total eonsumption 



United Sides 

Domestie Pioduetion: 

By-product ammonia 





Fixed atmospheric nitrogen 





Total production 






Chilean nitrate 





By-product ammonia 

1 19 




Fixed atmospheric nitrogen 





Total exports 

1 19 





Chdean nitrate 





By-product ammonia 





Fixed atmospherie nitiogen 





Total imports. 

l 12,039 




Toial consumption 

Domestic Pioduetion: 




Great Britain 

By-product ammonia 





Fixed atmospheric nitrogen 





Total production, 

Ex pores: 

Chilean nitrate 










By-product ammonia 




Fixed atmospheric nitrogen 





Total exports 




59)935 ' 


1 02 ^ 4 ° * 

















34 S 6 





































12.5 15 





339 j 444 















































39 , 3*33 









ports, and apparent consumption for Germany, United States, 
1 510 to 1925, are given below. 

tons of nitrogen) 
























447 ,'^^S 












1 9,064 






6 t,Boo 





































Domestic Production: 
By-product ammonia 
Fixed atmospheric nitrogen 








1 , 4^2 


Total pioduction 






Chilean nitrate 





By-ploduct ammonia 





Fix^ atmosphetic nltiogen 





Total exports 






Chilean nitrate 





By-product ammonia 





Fixed atmospheric nitrogen 





Total Impoits 

^ 5 A ^5 




Total consumption. ...... 





Domestic Production: 
By-product ammonia 


1,8 16 




Fixed atmospheric nitrogen 





Total production. 




i 6,995 

Exports — None 

Chilean nitrate 





By-product ammonia 





Fixed atmospheric nitrogen 





Total imports 





Total consumption 







Clulean nitrate 2^,107 

By-product amrnonla o 

Fixed atmospheric nitrogen -i^io 

Total im polls', 24,717 

Total consumption 43iSSi 

Domestic Production: 

By-p rod u ct ammoni a 1 3 ,220 

Fixed atmospheric nitiogen 198 

Total production I3i4l8 


Chilean nitrate ^ 807 

By-product ammonia 190 

Fixed atmoapheiic nitiogen Tio 

Total exports 


Chilean nitrate ^ 59)3^7 

By-product ammonia S>937 

Fixed atmospheric nitrogen 85 

Total imports.. ^ 65,389 

Total consumption 77,700 


(Expressed in net 
1916 I919 

Great Britain 

24,628 7B5IS 4)279 

5,958 22,115 7^536 

30,586 93,630 11,815 

54j03i 133)739 37, 841 


16,917 5,677 10,197 

1,485 19,Sqo 5,799 

18,402 25,477 15,996 

904 2,028 72 

261 335 67 

138 909 2 

1,303 3,272 141 

55,404 93,ool 6,861 

' 5,198 4,823 4,998 

1,652 1,318 1,264 

62,254 99, 142 

79)353 121,347 



i, 8 iJ 5 




2,1 30 








7 jH 4 

S >496 





























3 >257 




1 1,030 

U 599 












9 )C 39 












18 , IDO 

























T 7,952 








i,o 84 



37 ^ 3^9 





56.4 lo 








tons of nitrogen) 


















8, loo 







1 1,632 














20,00 1 











30,63 1 



40 1 
















2 rZO 































89,91 5 

68, 168 








This bibliography has been compiled with the hope that tlie 
readers whose interests have been aroused by the perusal oI the 
previous pages may find herein help in seeking reliable articles 
giving more technical and more detailed discussions of the various 
phases of the subject. It is selective rather than exhaustive, and 
when it was necessary to choose between two comparatively 
worthy works upon the same subject, in many instances the 
general accessibility and the references within the particular arti- 
cle have been influential in deciding which one should be included 
in this list. 


{Dealing with several phases of the subject) 

Haber, F. (Translated by A. B. Lamb). ‘’Thermodynamics 
of Technical Gas Reaaions.” Longmans, Green & Co., Lon- 
don & New York (1908). 

Considers arc process on pp. 265 ff; ammonia process on 
pp. 202 ff; and water-gas process on pp. 175 ff and 309 ff. 

Hack SPILL, Louis. ” L ’azote. La Fixation dc 1 ’ Azote Atmos- 
pherique et son Avenir Indus triel.” MassoA & Cie, Gauthier 
Villars et Cie, Paris (1922). 

Review of principal processes, description of technical manu- 
facture^ constructional details of various operating plants and 
an economic review of nitrogen fixation, describing various 
ammonium salts. 




Knox, Joseph. ” The Fixation of Atmospheric Nitrogen.'” Van 
Nostrand, New York, 2nd Edition, 1921. 

Discussion of reactions and thermodynamics involved. De- 
scribes commercial processes and furnaces. Good resume 
with bibliography. 

Lewis, G. N. and Rakd^ll, M, ‘’Thermodynamics.” 
McGraw-FIill, New York (1923). 

Nitrogen compounds discussed, pp. 556 ff. 

Martin, G. and Barbour, W. “Industrial Nitrogen Com- 
pounds and Explosives.” D. Appleton & Co., New York, 
2nd Edition, 1917. 

General review of whole subject (with references) discussing 
manufacture, properties and industrial uses, with numerous 
diagrams and photographs of apparatus. 

Munitions Inventions Department. Physical and Chem- 
ical Data on Nitrogen Fixation.” H. LI. Stationery Office, 
London, 1918. See C. A, 13, 1518 (1919). 

Compiled for use in connection with the synthesis and oxi- 
dation of ammonia. 

Nitrate Division, Ordnance Office, War Department and 
Fixed Nitrogen Research Laboratory. Report on the 
Fixation and Utilization of Nitrogen,” No. 2041. U. S. Gov- 
ernment Printing Office, 1922. 

Comprehensive report discussing world nitrogen situation, 
history, chemistry and construction and operating costs of 
various processes as well as U. S. Government nitrate plants. 
Bibliography for 1917-22. 

Nitrogen Products Committee. ” Final Report, 1919” Mu- 
niiions Inventions Department (London). 

Comprehensive discussion of all phases of the nitrogen 

Norton, T. H. UtUization of Atmospheric Nitrogen. Special 
Agents Series, No. 52, Department of Commerce and Labor. 
U. S. Government Printing Office (1912). 



Most complete treatise published up to 1912. Supplements 
Knox’s book on commercial and technical side. 

Partington, J. R. and Parker, L. H. The Nitrogen Indus- 
try.” Van Nosttand, New York (1922). 

Discusses Chilean nitrate, by-product and air- nitrogen indus- 
tries. A very readable but somewhat critical book, which 
is prone to digressions. Good section on ammonia Oxidation. 

U. S. Department of Commerce. “Nitrogen Survey.” 

Part L “The Cost of Chilean Nitrate.” IT. F. Bain and 
H. S. Mulliken. Published as Trade Information Bulletin 
No. 170 (1924). 

Supply and metliods as well as costs are considered. 

Part II. ’'General Review of the Nitrogen Situation in the 
United States.” H. A. Curtis. Published as Trade Informa- 
tion Bulletin No. 226 (1924). 

Nitrogen needs of the soil and the army; potential supply, 
production and consumption of nitrogen discussed. 

Part III. The Air-Nitrogen Processes,” J. M. Braham, 
Published as Trade Information Bulletin No. 240 (1924). 
Discusses commercial development, chemistry, costs, nature 
of products, and chances for improvement of various proc- 
esses; also the conversion of initial products into compounds 
Suited to agricultural, military and industrial needs. 

Part IV. ’‘The Nitrogen Situation in European Countries,” 
H. A. Curtis and F. A. Ernst, Published as Trade Informa- 
tion Bulletin No. 270 (1924). 

Waeser, B. (Translated by Fyleman, E.). ’'The Atmospheric- 
Nitrogen Industry with Special Consideration of the Produc- 
tion of Ammonia and Nitric Add,’^ J. & A. Churchill, 
(London), 1926. 2 Vols. 

Valuable for world economic statistics on nitrogen and survey 
of German industry and for many references to technical 
literature and patents, but contains numerous errors. 




Gilbert, C. G. ’'Political and Commercial Control of the 
Nitrogen Resources of the World.” Chem. & Met. Eng. 22, 
pp. 443-48; pp. soi^; pp. 557-9 (1920). 

Economic discussion and review with bibliography. 

Haber, F, ” Les Prix Nobel en 1919-20.” Stockholm, 1922. 
Naturwlssenscliaften jo, 1041 (1922). 

History of nitrogen fixation. 

JOAJEs, C. PL ” Muscle Slioals Hydro-Electric Develop n lent.” 
Chem. & Met. Eng. 22, 417-9 (1920). 

Lakdis, VV. S. “Fixation of Atmospheric Nitrogen.” J. Ind. 
Eng. Chem. 7, 433-8 (1915). 

General, but emphasis is on process of American Cyanamid 

Maxted, E. B. Process of rhe Nitrogen Industry in 1925.” 
Chem. Age (London) 13, 644-6 (1925). 

Important articles and patents of year. 

Parsons, C. L. and Committee. Nitrate Supply Committee 
Recommendations on Synthetic Nitric Acid for the Govern- 
ment with Reports on Various Methods.” J. Ind. Eng. Chem. 
p, 829-41 (1917). 

Summers, Leuand L, ” Fixation of Atmospheric Nitrogen.” 
Trans. Am. Electrocliem. Soc. 27, 339-384 (1915). 


The Fixed Nitrogen Research Laboratory, Bureau of 
Chemistry and Soils, Dep.wtment of Agriculture, has 
compiled a very extensive unpublished bibliography on nitro- 
gen fixation which may be consulted in its Library at Wash- 
ington, D. C. 

Boyce, J. C, '’Bibliography on the Production of Synthetic 
Nitric Acid and Synthetic Ammonia.” Met Chem. Eng. 



328-37 (1917)- Literature references 1786-1917. Abstracts 
of British, German, French and U. S. patents 1859-1917. 

Creighton, EIenry J. M. ” How the Nitrogen Problem has 
been Solved.” J. Frank. Inst. 18 ’/, pp. 377-408; pp. 599-610; 
pp^ 70S-755 (^ 919 )- 

Elaborate discussion of various processes and their relative 
efficiencies. Bibliography of selected references 1786-1919 
(19 pages). 

Hosmer, Helen R. ” Literature of the Nitrogen Industries, 
1912-1916.” J. Ind. Eng, Chem. p, 424-35 (1919). 

Critical bibliography. 


Birkeland, Kr, ” On ihe Oxidation of Atmospheric Nitrogen 
in Electric Arcs.” Trans. Faraday Soc. 2, 98-116 (1906); 
C. A. J, 821 (1907). 

Summary of work of others in this field and discussion of 
process used at Notodden, Norway. 

Eyde, Samuel. ” Oxidation of Atmospheric Nitrogen and De- 
velopment of the Resulting Industries of Norway.” 8th 
Intcrnat’l Cong. Applied Chem. 28 , 169-181 (1912); Ab- 
stract in J. Ind. Eng. Chem. 4, 771-4 (1912). 

Haber, F. and Koenig, A. ” Oxidation of Atmospheric Nitro- 
gen.” Z. Elektrochem. 16 , 1 1-25 (1910). 

Careful review of papers and patents from June 1907 to 
June 1909. 

Haber, and others in 4 articles. “Oxidation of Nitrogen in the 
High potential Arc.” Z. Elektrochem. 16 , No. 19, pp. 789- 
826 (1910). Reviewed in C. A. 5, 2033-4 (191^)- 

Hausser, F. “Oxidation of Nitrogen in Explosive Gas Mix- 
tures.” Z. Ver. deut. Ing. ^ 6 , 1157-64 (1912). Reviewed in 
C. A. 6 , 2713 (1912). 

Discusses his process for fixation of nitrogen by explosion 
of coke oven gases. 



Karrer, S. Phenomena in the Electric Arc Process of Nitro- 
gen Fixation.” Trans. Am. Electrochem. Soc. 48, 223-32 

Discusses dissociation, ionization, excitation, radiation and 
energy transfer. 

Koenig, A. ” Uber die Elektrische Aktivierung des Stickstoffs.” 
Z. Elektrochem. 21, 267-86 (1915). 

Full discussion of subject of active nitrogen and Its relation to 
nitrogen fixation. 

Lewis, G. N, and Eugar, A. The Equilibrium between Nitric 
Acid, Nitrous Acid and Nitric Oxide,” J. Am. Chem. Soc. 
S3, 292-9 (1911). 

Moscicki, Ignacy, ” Preparation of Nitric Acid from the Air.” 
Electrochem. & Met. Ind. 5, 491-4 (1907). 

Describes Mosdcld ate furnace. 

ScHdNHERk, D. ” The Manufacture of Saltpeter from the Air 
by the Process of the B. A. S. F.” Trans. Am. Electrochem. 
Soc, 16, 131-64 (1909). 

Use Schbnhcrr arc furnace at Christianssand. 

Scott.’, E. Kileurn. ’‘Nitrogen Fixation Furnaces.” Trans. 
Am. Electrochem. Soc. 221-54 (1919). 

Classification and review of arc furnaces. 

Scott, E, Kilburn. ’‘Manufacture of Synthetic Nitrates by 
Electric Power.” J. Soc. Chem. Ind. jd, 771-7 (1917). 
Description aiid cuis af yarluus I urn aces. 

SiLEERMANN, ” Elelctrisclie Behandlung von Gasen ” 

(Leipsig, 1922). 

Abstraci of German patent literature including arc and silent 
discharge processes for production of nitric oxide, ammonia 
and cyanide, 

S'rEiNMSTz, C. P. ” Theoretical Study of Nitrogen Fixation by 
the Electric Arc.” Chem. & Met Eiig. 22, pp. 299-304; 
353-7; 4.SS-62 (1920). 



Vanderpoel, Jules. ”A French Plant for the Fixation of At- 
mospheric Nitrogen,” Chem. & Mei. Eng. p, 102-3 and 
196-8 (1911). Commercial application of Pauling process. 

Z.” ” Process and Apparatus for the Electrical Fixation of Ni- 
trogen.” Z. Elektrochcm. 21 , 2I1-21 (1914); C. A. p, 756 


P a tent resume. 


B REDIG, G.j Frankel, W. and Wtlke, E. On Lime Nitro- 
gen.” Z. Elektrochem. 13 , 69-75 (1907)- 
Action of various catalysts on the nitrification of carbide. 

Caro, N. ’‘The Cyanamid Industries and Related Processes.” 
Z. angew. Chem, 22 , 1178—82 (1909); C. A. 3 , 2088 (1909). 
Frank and Caro processes and effect of impurities in the car- 
bide and nitrogen are discussed. 

Frank, A. ’‘On the Utilization of the Atmospheric Nitrogen 
in the Production of Calcium Cyanamide and Its Use In 
Agriculture and Chemistry.” Chem. News p7, 289-92; 303-6 
(1908). Also in Trans, Faraday Soc. 4 , 99-119. 

Frazer, John. The Muscle Shoals Ply dro- Electric Nitrogen 
Fixation Plant” CMmie et Industrie p, 615-21 (1923). 

Gall, H, ” The French Cyanamide Industry.” Chimie et In- 
dustrie, 6 , 430-9 (1921). 


Jacob, R. D., Krase, H. J., and Brahm, J. M. " Decomposi- 
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16 , 684-8 (1924). 

Erase, PI. J., and Yee, J. Y. ’‘The Mechanism and Thermo- 
chemistry of the Reaction between Calcium Carbide and 
Nitrogen.” J. Am, Chem. Soc. 46 , 1358-66 (1924). 


Landts, W. S. “ The Fixation of Atmospheric Nitrogen.” Met. 
& Chem. Eiig. 13 , 213-20 (1915). 

Description of process and plant of American Cyanamid Co. 

Landis, W. S. ‘’The Production of Ammonia from Cyanamid.” 
J. Ind. Eng. Cliem, 8 , 156-60 (1916). 

Chemistry and cosis. 

pRANKE, E. J. ” Cy ana mide — Manufacture, Chemistry and 
Uses,” The Chemical Publishing Co., Easton, Pa., 1913, 
106 pp. 

Pranke, E. j. ” The Present State of the Cyanamide Indus- 
try.” J. Ind. Eng. Cliein. 6 , 415-9 (1914). 

Considered from fertilljjcr standpoinv. 

Thompson, M. deK. and Lombard, R. H. ” Equilibrium of the 
System Consisting of Calcium Carbide^ Calcium Cyanamide, 
Carbon and Nitrogen.” Met. Chem. Eng. 8 , 617-20 and 
682-4 (1910). 

Washburn, F. S. “The Cyanamide Process,” Trans. Am. 
Electrocliem. Soc. 27, 385-407 (1915). Also in Chem. & Met 
Eng. 13 , 309-H (19^5)- 
Compared with other fixation processes. 


Anon. “Manufacture nf Synthetic Ammonia at Oppau, Ger- 
many.” Chem. & Met Eng. 24 ^ pp. 305— B; 347-50; 391-4 


I. Preparation and purification of hydrogen- nitrogen mix- 
ture. II. Synthesis. IIL Preparation of ammonium salts 
and plant layout. 

Barnitz, H, L. ” Electrolytic Production of Hydrogen.” Chem, 
Met Eiig. 14 , 391-5 (19^6) and 22 , 201-6 (1920). 

Review and advantages of various types of cells. 


Bernthsen, H, a. Synthetic Ammonia.” Trans. 8th Cong. 
Applied Chemistry 28 , 182-201 (1912). Also in J. Ind. Eng. 
Chem. 4 , 760-7 (1912). 

Historical and descriptive review of Haber process. 

Claude, G. ” The Mamifacture of Hydrogen by the Partial 
Liquefaction of Water Gas and Coke-Oven Gas.” J. Ind. 
Eng. Chem. 14 , 1118-9 (1922). 

His apparatus described, 

Claude, G. ”The Synthesis of Ammonia at High Pressures.” 
Chimie et industrie 4 , 5-18 (1920). 

History of his process. 

Ellis, Carleton. "The Hydrogenation of Oils — Catalyzers 
and Catalysis and the Generation of Hydrogen and Oxygen.” 
D. van Nostrand Co., 2nd Edition (1919). 

Pages 444-60 j applicable to ammonia synthesis problems. 

Haber, F, ’’Synthetic Production of Ammonia.” Z, angew, 
Chem. 27, 473-7 (1914). 

History and thermodynamics of his process. 

Haber, F. and LeRossignol, R. ” Uber die Techuische Dar- 
stellung von Ammoniak a us den Elementen.” Z. Elektro- 
chem. jp, 53-72 (1913). Good abstiact in Met & Chem. 
Eng. II, 211-4 (1913)- 
Fundamentals of the process. 

Jones, C. H. ’’Nitrogen Fixation by the Haber Method.” 
Chem. & Met Eng. 22 , 1071-5 (1920). 

Especially at U. S. Nitrate Plant No. i. 

Keyes, F. G. and Brownlee, R. B. ’’The Thermodynamic 
Properties of Ammonia.’^ John Wiley Sc Sons, Inc. (1916). 

Larson, A. T. et ah ’‘Contributions to the Study of Ammonia 
Catalysts.” (In V parts). Chem. Sc Met Eng. 26 , 493-7; 
555-60; 588-93; 647-54; 683-s (1922). 

Larson, A. T. ‘’ The Ammonia Equilibrium at High Pressures.” 
J. Am. Chem. Soc. 46 , 367-372 (1924). 

450 to 500° C and 300 to 1000 atmospheres. 



Lheure, M. “Synthetic Ainiiioiiia by the Ckuje PrciceiiA 
Tianslation in Chem. Sc Met. Eng. 41)8-701 1 i9-j)- 
Cost and yield figures of Claude and Haber procca 

Maxted, E. B. ” The Synthesis of Aniiiii/niii and I is OMuatkii 
10 Nitric Acid.” J. Soc. Chem. Ind. j6, 777- Sa (.1917). 

NoRTo^^ F. E. ‘’Tile Separation of Air in 10 Oxygen and Xi- 
fiogeii.” Chem. & Met. Eiig. aj, 511-8 (19JO). 

Taylor, H. S. “ The Production of Nitrogen and FI\ diogeii for 
Synthetic Ammonia Manufacture.” Client. Sc Met. Eag. 
1263-6 (1922). 

Discusses various processes. 

Teed, P. L. ” Chemistry and Manufacture of Hydrogen.” Ed- 
ward Arnold (London), 1919. 

Engineering standpoint. 

Tour, R, S. ’’The German and American Syntlictic-Ammonki 
Plants.” I to IV. Chem. Met. Eng. id, pp. 245-S; 

359-62; 411-1S; 463-5 (1922). 

Inclusive descriptions giving costs. 

Weaver, E. R. “Production of Hydrogen b}" the Thermal De- 
composition of Oil.” Chem. & Met. Eug. :?S, 764-S; 939-45; 
1072-5 (1923). 

Method, purity and costs given. 

Zambianchi, a. ’‘ Fauser Synthetic Ammonia Process,” Chem. 
Age (New York), jj, 413 (1923). 


Anon, ’‘The Ostwald Process for Making Nitric Acid from 
Ammonia.” Chem. &Met. Eng. ii, 438-42 ( 19 M)- 


Curtis, H. A. ” The Oxidation of Ammonia. The Wo tic of the 
Sheffield Experiment Station.” Chem. & Met. Eng. 27, 699- 

703 (1922), 

Parsons, C. L. ” Nitric Acid from Ammonia.” J. Ind. Eng. 
Chem. Jp, 789-94 (1927)- 

Parsons, C. L. “ Commercial Oxidation of Ammonia to Nitric 
Acid.’’ J. Ind. Eug. Chem. ii, 541-52 (1919). 

Review of progress. 

Perley, G. a. ” The Catalyst for the Oxidation of Ammonia.^’ 
Chem. & Met. Eng. 22, 125-9 (1920). 

Discussion of various types of catalysts. 

Perley, G. a. ’‘The Commercial Oxidation of Ammonia.’’ J. 
Ind. Eng. Chem. J2, 5-16 and 119-29 (1920). 

Taylor, G. B, “ Some Economic Aspects of Ammonia Oxida- 
tion.” Chem. & Met. Eng. 2 ( 5 , 1217-9 (1922). 

Toniolo, Carlo. “ Absorption of Nitrogen Oxides from Am- 
monia Oxidation.” Chem. & Met. Eilg. 54, 92-5 (1927). 

XeisberC, F. C. “The Ostwald Process of Oxidizing Ammonia 
to Nitric Acid.” Met. & Chem. Eng. is, 299-304 (1916). 
Review of literature and patents with cost estimates. 


Erlwein, G. “Calcium Cyanamide; A New Starting Point in 
the Cyanide Manufacture.” J. Soc. Chem. Iiid. 22, 794 

Erase, H. J. et al. “ How to Prevent the Caking of Crystals.” 
Chem. Met. Eng, 52, 241-3 (1925). 

Graining and oiling of ammonium nitrate. 

Krase, N. W. and Gaddy, V 7 L. ” Synthesis of Urea from 
Ammonia and Carbon Dioxide,” J. Ind. Eng. Chem. 14, 
611-6 (1922), 



Landis, W. S. “Production of Ammoma from CyanaliliJr." 
J. Ind, Eng. Cliem. 5 , 156-60 (1916). 

Porter, H. C. “ Coal and Coke By-Plodiicts ai a Source ti 
Fixed Nitrogen.” Chem. ^fct. Eng. jj, 470-5 (icjib). 

Symmes, E. M. The Manufacture of Amnionluni Nitrate,” 
Chem. Met. Eng. 26, 1069-74 (1922). 

Webb, PI. W. ” The Absorptioii of Nitrous Gases.” Edward 
Arnold & Co., London, 1923. 

Theory and practice well balanced. 

Werner, Emil A. ” The Chemistry of Urea,” Alonograph on 
Biochemistry. Longmans, Green & Co. (1923). 


Anon. ’’Patents of Invenrions Referring to the Extraction of 
Nitrate.” Caliche i, 25, 64 (1919), 

Summary from 1853-1907. 

Bertrand, A. ” Nitrate Industry in Chile.” Chem. Alet. Eng. 
655-9 (1920). 

Hobsbawn, j. B. ’‘Nitrate Industry in Chile.” Chem. Met. 
Eng. 16, 253-9 (1917)- 

Marco, J. “Production Costs of Chilean Nitrate.” J. Ind, 
Eng. Chem. 77,780 (1919), 


LipM.AN, J. G. ” The Fixation of Atmospheric Nitrogen by 
Bacteria.” U. S. Department of Agriculture Bulletin No. 3 i, 
pp. 146-60 (1904). 

Greaves, J. E, ” Azofication.” Soil Science d, 163-217 (igiS); 
Expt, Sta. Rec. 41, 124. 



Review of literature on nonsymbiotic nitrogen fixation. Good 
bibliography included. 

WaksmA)^, Seliman a. “ Principles of Soil Microbiology.” Wil- 
liams & Willcins (1927). 

Chapter 12 is on Fixation of Atmospheric Nitrogen. Has a 
bibliography of 2543 references (880 pages long). 


Maxted, E, B, "Ammonia and the Nitrides — With Special 
Reference to T leir Synthesis.” P- Blakiston’s Sons & Co. 


The Barrett Company, New York. 

Publishes yearly pamphlet on Sulphate of Ammonia Statistics. 

Ernst, F. A. and Sherman, M. S. ” The World’s Inorganic 
Nitrogen Industry.” Ind. Eng. Chem. iq , 196-204 (1927). 

Harker, J. a. ’’ Statistical Supplement to the Final Report^ 
of the Nitrogen Products Committee” (London), 1921. 
Nitrogen world statistics to year 1920. 

International Institute of Agriculture of Rome. " Pro- 
duction et Consommation des Engrais Chimiqiies dans la 
Monde, 1924.” 

Also publishes statistics on agriculture, clieniical products 
useful in agriculture, international trade in fertilizers, etc., 

Lambert, E, and M. “ Annualre Statlsque des Engrais et Pro- 
duits Chimiques Destines a I’Agriculture,” Paris. 

Tables published yearly which give many statistics for nitro- 
gen compounds. 

U. S. Department or Commerce Reports. 


Absoi-vtluii.’i\oniii Removil, 6i. 
Alisi)r|)liim towers, 27, 48, 
Alr-byUi-t>R);)i linnicr, fig, 72. 
Aiiicrii'Jii Cyaiimiiid Co., 15. 
Ai)u;ri)’a» Niiru^u)) Products Co., 14. 
aqua, 51. 
by-proiluct, 1. 

conversion proilucis of, 100. 
cyananiiilc, 39. 
uquilibriuii) Wttl), 53. 
nitrogen, Ui8. 
iixiilatio)! of, 40, 47, 108. 
renioi'al, g, 12,61. 


nitrate, 10, 48, 102, 113, 
phosphate, 102, 113. 
sulphate, toi. 

Aiiiiiio-phijs, 113. 

Are furnacesj 12, 24. 

Are process, 13, 21, 129. 
vnsts, 90. 

Atniiisphci’ic Nitrogen Corp., 121, 

1 22, 

Atimisiiherie Prmliiets Cn., 11. 
Australia, >26. 

Autoclaves, 39) 44. 

Badisehc Analin und Soda Fabrik, 
j 68, I06. 

Biutei’ial fixjtion, fi, 

Bain anil Mullikcii, 88. 

Belgium, 126. 

Bibliog raphy , 138. 

Birkelaiiil aod Eyde furnace, 12, 

24, 26. 

Boyles law, 75 - 

Bosch process, S4, 

Bradley and Lovejqy, 12. 

Braail, I26. 

Bucher, Prof. J. E., 18. 

an 111 10 Ilia, 1. 
hydiogen, 67. 

Calcium carbide furnace, 31, 42. 
Calcium cyanainiilc, 58. 

CalctU))) nit) ale, 115. 

Capital charges, 92. 

Carb))n dioxiile roiioval, 65. 

Carbon monoxide, 
conversion of, 64, 
rcjiioval, 65. 

Casale mcfbotl, 6t, 86. 

Catalyst, 55, >08, i)o. 

Cells, Electrolytic, 66. 

Clic)))ical Fuunciati))n Inc., S7. 

Chile nitrate, 2, 7, Sg^ 112, 117, 127. 
City gas plants, 98. 

Claude method, 61 , 85. 

Cuiniiiercial Solvents Corp., 67, 94, 
121, 1 24. 

Co)npr2ssibility, 75. 

Compressor caleulatiinis, 76 
C’cncciitration of nitric aei)l, 1 lo. 
Condensers, 83. 

Consumption, nitrogen) 7 , 135* 
Conventer. Aiimionia, 79. 


ammonia oxidation, )i2. 

Chile iiitrJtc, 127. 
nitrogen fixation processes, 89. 
Crookrs, Sii William, 6. 

Cyanainid, 38. 



Cvanaiiiiilc process, 7, 14, 18, 30, 90. 
Cyclic system, 61. 

Czechoslovakia, 126. 

Densities, Gas, 64, 74- 
Diaimnottium pljobpliaic, t\ 6 . 

Direct synthetic aminunia process, 9, 
16, S 3 > ' 31 - 
costs, 90. 

flow diagram, 69. 

Electiical fixation, 21, 

Electrolytic cells, 66. 

Englaml, >20, 134. 

Equilibriinii, aiiitnoiiia, 53. 
Explosives, 5. 

Export tax. Chile iiitratei S9. 

Kauscr method, 61, 87) 93. 
Fertilizers, 39. 

France, 124, 134. 

Frank — Caro, >4. 

Fulminate of Mercury, 9. 

G as densities, 64, 74. 

GaskeC 82. 

GJs wells, 67, 97. 

General Chemical Co., 17. 

Germany, 120, 134. 

Great Britain, 120, 134. 

Great Western Electro-Chemical Co., 
94, 121. 

Guggenheim process, 88. 

Goye, 13. 

Gypsum process, 106. 

Haber, Prof. Fritz, ij. 

Habei -Busch process, 84. 

Hauser processj ig. 

Hobsbaun, 127. 

Hooker Electrochemical Co., 94, 122. 
Hopewell, 122, 


air burner, 69, 72. 
by-product, 67, 93, 57. 
electrolytic, 66 . 
requirements, 69. 
sources of, 64. 

■water gas, 6y. 

I)npcridl Chemical Industries Ltd., 

Industrial r level) )|inrent, 91. 

Italy, 12 5, 134, 

Japan, 125, r3J. 

Kalkstickstoff, 3 8 . 

Knapsack plant, 50. 

Lazolc Inc., r2r* 

Lcuna plros, 116. 

Lcunaplioska, r r 6. 

Lcuna-salpeter, iij. 

LeunJ Werke, 84, ro6. 

Lrljeoroth process, 68* 

Lime kilns, 30, 42. 

Lirrre nitrogen, 3L 
Liquid air process, 

Claude, 33, 35, 42. 

Linde, 33. 

Jifariurcs, r , 6. 

MarignaC plant, 50. 

Mathicson Alkali Works, 93, r2r. 
Merseburg plant, 84, 106. 

Methane, 67. 

MitteUlcutschc Tickst))ff Werke, 92. 
Monoarnrrronir)iu phosphate, rr6. 
Moscickt, r3. 

Musde Shoals, fsee U. S. Nitrate 
Plant) . 

Mr’spratt, Sir Max, 100, rr7. 

National Defense Act, >6. 

Niagar-a Arnmorria Co., 94, 121. 

Oxidation, Am-noiiia. 40, 47, 108. 
Oxidizcis, 109. 

Pacific Nitrogen Corp., 121. 
Pauling arc furnace, 13, 25, 28. 
Phosphate of mmiionia, 102, 113. 
Phosphoric acid, 68, 

Phospliorus, 68. 

Picric acid, 9. 

Picstcrit2, Germany, 68, 92- 
Poland, 126. 

Tax. Chile nitrate, 89. 
Temperature, effect of, 54, 63. 
Tlieniiatomic Carbon Co., 67. 
Toulolisc, France, 124. 
Trinitrotoluene. TNT, 9. 

Uni fed States, 120, 134. 

U. S, Nitrate Plant #1, 16, 

U. S. Nitiate Plant #2, 1 j. 
absorption to we is, 48. 
ammonia autoclave, 44, 



Nitraiil Ltd.) 


ammoniuiii) 10, 48) 102, >13. 

Chile, 2, 7, 89. > >2, 117, 127 - 

potassium, 2. 

Nitrate of liiiN, iij- 
Nitrate nitrogen, 

Nitric acid, 24 ) 9 'i 
Ci’iicentration, iii- 
Nitric oxidcj 22, 108. 

Nitride process, 8. 

Nitrifying oveiis, 36, 44, So. 
Nitm glycerine, 9. 


a»iiinonia, 108. 

atmospheric, 2, 8, 

by-product, a, 8, 

burning liyilrogen in air, 6. 

coniine rcial soutecs, i. 

demand for fixed, 117. 

fixed, 9. 

nitrate, 108. 

organic, i. 

producer gas, 65. 

waste, 95. 

Nitrogen Products Co,, 18, 
Nitrolec, 13. 

Nitrolini, 38. 

Norsk Hydro, 13, 91. 

Norway, 12^. 

Norwegian saltpeter, 27. 
Notoddeil, 12. 

PoIIitt. Col,, 1 1 S, 
Potassiuin-aminonium nitrate, 1 15. 
Power consumption, 20, 95. 


effect of, 54, 63. 
vessels. Si. 

Producer gas, 65, 

Promoters, 55. 

Purification, 6j. 

Refrigeration, 62. 

Rjiikan plant, 13, 25. 

Roessler Hasslachcr Chemical Co., 
94, 121. 

Russia, 126. 

Saltville, Va., 18. 

Schonherr furnace, 13, 25. 
fSen'es system, 61. 

Smokeless powder, 9. 

Southern Electro-Clicmical Co., 13. 
Space time yield, 59. 

Space velocity, 57, 

Spain, 126. 

Statistics, 117. 

Stockholm Superfosfat Fabrik, 51, 

Sulphate of ammonia, 101. 

Sweden, 125, 

,Syiithcsis chamber, 79. 

Synthetic Ammonia and Nitrates Ltd., 



aiiiiiiiiniuiii iiitrale, 48. 
ailiniimia oxid//.L*rP, 47, > lo. 
carbide ovens, 42, 
lime kilns, 42. 
liriiiid air plant, 4i. 
nitrifying ovens, 44. 

U. S. Cheniieal Plant -^4, 18. 

Urea, 51, 102, 107. 

w atcr gas, 64. 
Wielgolaski, 13. 

Y ugoslavia, 1 2 6.